PATENT DOCUMENT

Publication Number: US-11755196-B2
Application Number: US-202117515281-A
Country: US
Kind Code: B2

Title: Event recognition

Abstract:
An electronic device, while displaying application content for a first application on a touchscreen display, detects an input comprising one or more touches on a region of the touchscreen display that includes the application content of the first application. In response to detecting the input comprising the one or more touches, the electronic device, in accordance with a determination that the one or more touches correspond to a system gesture for switching applications, replaces display of the first application with a second application without delivering information corresponding to the one or more touches to the first application; and in accordance with a determination that the touches do not correspond to a system gesture, delivers the information corresponding to the one or more touches to the first application.

Claims:
What is claimed is: 
     
       1. A method comprising:
 at an electronic device with a touch-sensitive display:
 displaying, by the electronic device, on the touch-sensitive display, a user interface of a first software application; 
 while displaying the user interface of the first software application, detecting, by the electronic device, one or more first touch inputs on a region of the touch-sensitive display that includes the user interface of the first software application; and 
 in response to detecting the one or more first touch inputs:
 in accordance with a determination that the one or more first touch inputs correspond to a system gesture for switching applications, replacing, by the electronic device, display of the user interface of the first software application with display of a user interface of a second software application without delivering information corresponding to the one or more first touch inputs to the first software application, wherein the second software application is different from the first software application; and 
 in accordance with a determination that the one or more first touch inputs do not correspond to a system gesture, delivering, by the electronic device, the information corresponding to the one or more first touch inputs to the first software application. 
 
 
 
     
     
       2. The method of  claim 1 , wherein, in accordance with the determination that the one or more first touch inputs do not correspond to a system gesture, the first software application performs an operation in response to the information corresponding to the one or more first touch inputs being delivered to the first software application. 
     
     
       3. The method of  claim 2 , including processing the one or more first touch inputs using one or more gesture recognizers of the first software application and one or more system gesture recognizers to determine whether the one or more first touch inputs correspond to the system gesture for switching applications. 
     
     
       4. The method of  claim 1 , including processing the one or more first touch inputs using one or more system gesture recognizers to determine whether the one or more first touch inputs correspond to the system gesture for switching applications. 
     
     
       5. The method of  claim 4 , wherein the one or more system gesture recognizers are associated with an operating system that is different from the first software application. 
     
     
       6. The method of  claim 1 , including, prior to detecting the one or more first touch inputs, displaying the user interface of the first software application without concurrently displaying the user interface of the second software application. 
     
     
       7. The method of  claim 1 , wherein replacing display of the user interface of the first software application with display of the user interface of the second software application includes ceasing to display the user interface of the first software application. 
     
     
       8. The method of  claim 1 , wherein the second software application is a next software application following the first software application in a sequence of applications with retained state information. 
     
     
       9. The method of  claim 1 , including:
 while displaying the user interface of the second software application, detecting one or more second touch inputs on a region of the touch-sensitive display that includes the user interface of the second software application; and 
 in response to detecting the one or more second touch inputs:
 in accordance with a determination that the one or more second touch inputs correspond to the system gesture for switching applications, replacing display of the user interface of the second software application with display of a user interface of a third software application without delivering information corresponding to the one or more second touch inputs to the second software application; and 
 in accordance with a determination that the one or more second touch inputs do not correspond to a system gesture, delivering the information corresponding to the one or more second touch inputs to the second software application. 
 
 
     
     
       10. The method of  claim 9 , wherein the second software application is a next software application following the first software application in a sequence of applications with retained state information, and the third software application is a next software application following the second software application in the sequence of applications with retained state information. 
     
     
       11. The method of  claim 9 , wherein determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs correspond to the system gesture for switching applications performed in a first direction, and wherein:
 in accordance with a determination that the one or more second touch inputs correspond to the system gesture for switching applications performed in the first direction, the third software application is different from the first software application; and 
 in accordance with a determination that the one or more second touch inputs correspond to the system gesture for switching applications performed in a second direction that is opposite the first direction, the third software application is the first software application. 
 
     
     
       12. The method of  claim 11 , wherein:
 the system gesture for switching applications performed in the first direction includes a swipe gesture in the first direction; and 
 the system gesture for switching applications performed in the second direction includes a swipe gesture in the second direction that is opposite the first direction. 
 
     
     
       13. The method of  claim 1 , wherein determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs correspond to a first type of system gesture for switching applications, and the method includes:
 in response to detecting the one or more first touch inputs:
 in accordance with a determination that the one or more first touch inputs correspond to a second type of system gesture for switching applications, replacing display of at least a portion of the user interface of the first software application with a user interface of an operating system without delivering information corresponding to the one or more first touch inputs to the first software application, wherein the operating system is different from the first software application and from the second software application. 
 
 
     
     
       14. The method of  claim 13 , wherein:
 determining that the one or more first touch inputs correspond to the first type of system gesture for switching applications includes determining that the one or more first touch inputs include a swipe gesture in a first direction; and 
 determining that the one or more first touch inputs correspond to the second type of system gesture for switching applications includes determining that the one or more first touch inputs include a swipe gesture in a second direction that is perpendicular to the first direction. 
 
     
     
       15. The method of  claim 13 , wherein:
 determining that the one or more first touch inputs correspond to the first type of system gesture for switching applications includes determining that the one or more first touch inputs include a swipe gesture; and 
 determining that the one or more first touch inputs correspond to the second type of system gesture for switching applications includes determining that the one or more first touch inputs include a pinch gesture. 
 
     
     
       16. The method of  claim 1 , wherein:
 in accordance with a determination that the electronic device is operating in a first mode:
 determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs match a first gesture definition for the system gesture for switching applications; and 
 
 in accordance with a determination that the electronic device is operating in a second mode:
 determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs match a second gesture definition for the system gesture for switching applications, wherein the second gesture definition is different from the first gesture definition. 
 
 
     
     
       17. An electronic device, comprising:
 a touch-sensitive display; 
 one or more processors; and 
 memory storing one or more programs for execution by the one or more processors, the one or more programs including instructions for:
 displaying, by the electronic device, on the touch-sensitive display, a user interface of a first software application; 
 while displaying the user interface of the first software application, detecting, by the electronic device, one or more first touch inputs on a region of the touch-sensitive display that includes the user interface of the first software application; and 
 in response to detecting the one or more first touch inputs:
 in accordance with a determination that the one or more first touch inputs correspond to a system gesture for switching applications, replacing, by the electronic device, display of the user interface of the first software application with display of a user interface of a second software application without delivering information corresponding to the one or more first touch inputs to the first software application, wherein the second software application is different from the first software application; and 
 in accordance with a determination that the one or more first touch inputs do not correspond to a system gesture, delivering, by the electronic device, the information corresponding to the one or more first touch inputs to the first software application. 
 
 
 
     
     
       18. The electronic device of  claim 17 , wherein, in accordance with the determination that the one or more first touch inputs do not correspond to a system gesture, the first software application performs an operation in response to the information corresponding to the one or more first touch inputs being delivered to the first software application. 
     
     
       19. The electronic device of  claim 18 , wherein the one or more programs include instructions for processing the one or more first touch inputs using one or more gesture recognizers of the first software application and one or more system gesture recognizers to determine whether the one or more first touch inputs correspond to the system gesture for switching applications. 
     
     
       20. The electronic device of  claim 17 , wherein the one or more programs include instructions for processing the one or more first touch inputs using one or more system gesture recognizers to determine whether the one or more first touch inputs correspond to the system gesture for switching applications. 
     
     
       21. The electronic device of  claim 20 , wherein the one or more system gesture recognizers are associated with an operating system that is different from the first software application. 
     
     
       22. The electronic device of  claim 17 , wherein the one or more programs include instructions for, prior to detecting the one or more first touch inputs, displaying the user interface of the first software application without concurrently displaying the user interface of the second software application. 
     
     
       23. The electronic device of  claim 17 , wherein replacing display of the user interface of the first software application with display of the user interface of the second software application includes ceasing to display the user interface of the first software application. 
     
     
       24. The electronic device of  claim 17 , wherein the second software application is a next software application following the first software application in a sequence of applications with retained state information. 
     
     
       25. The electronic device of  claim 17 , wherein the one or more programs include instructions for:
 while displaying the user interface of the second software application, detecting one or more second touch inputs on a region of the touch-sensitive display that includes the user interface of the second software application; and 
 in response to detecting the one or more second touch inputs:
 in accordance with a determination that the one or more second touch inputs correspond to the system gesture for switching applications, replacing display of the user interface of the second software application with display of a user interface of a third software application without delivering information corresponding to the one or more second touch inputs to the second software application; and 
 in accordance with a determination that the one or more second touch inputs do not correspond to a system gesture, delivering the information corresponding to the one or more second touch inputs to the second software application. 
 
 
     
     
       26. The electronic device of  claim 25 , wherein the second software application is a next software application following the first software application in a sequence of applications with retained state information, and the third software application is a next software application following the second software application in the sequence of applications with retained state information. 
     
     
       27. The electronic device of  claim 25 , wherein determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs correspond to the system gesture for switching applications performed in a first direction, and wherein:
 in accordance with a determination that the one or more second touch inputs correspond to the system gesture for switching applications performed in the first direction, the third software application is different from the first software application; and 
 in accordance with a determination that the one or more second touch inputs correspond to the system gesture for switching applications performed in a second direction that is opposite the first direction, the third software application is the first software application. 
 
     
     
       28. The electronic device of  claim 27 , wherein:
 the system gesture for switching applications performed in the first direction includes a swipe gesture in the first direction; and 
 the system gesture for switching applications performed in the second direction includes a swipe gesture in the second direction that is opposite the first direction. 
 
     
     
       29. The electronic device of  claim 17 , wherein determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs correspond to a first type of system gesture for switching applications, and the one or more programs include instructions for:
 in response to detecting the one or more first touch inputs:
 in accordance with a determination that the one or more first touch inputs correspond to a second type of system gesture for switching applications, replacing display of at least a portion of the user interface of the first software application with a user interface of an operating system without delivering information corresponding to the one or more first touch inputs to the first software application, wherein the operating system is different from the first software application and from the second software application. 
 
 
     
     
       30. The electronic device of  claim 29 , wherein:
 determining that the one or more first touch inputs correspond to the first type of system gesture for switching applications includes determining that the one or more first touch inputs include a swipe gesture in a first direction; and 
 determining that the one or more first touch inputs correspond to the second type of system gesture for switching applications includes determining that the one or more first touch inputs include a swipe gesture in a second direction that is perpendicular to the first direction. 
 
     
     
       31. The electronic device of  claim 29 , wherein:
 determining that the one or more first touch inputs correspond to the first type of system gesture for switching applications includes determining that the one or more first touch inputs include a swipe gesture; and 
 determining that the one or more first touch inputs correspond to the second type of system gesture for switching applications includes determining that the one or more first touch inputs include a pinch gesture. 
 
     
     
       32. The electronic device of  claim 17 , wherein:
 in accordance with a determination that the electronic device is operating in a first mode:
 determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs match a first gesture definition for the system gesture for switching applications; and 
 
 in accordance with a determination that the electronic device is operating in a second mode:
 determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs match a second gesture definition for the system gesture for switching applications, wherein the second gesture definition is different from the first gesture definition. 
 
 
     
     
       33. A non-transitory computer readable storage medium storing one or more programs, the one or more programs comprising instructions that, when executed by an electronic device with a touch-sensitive display, cause the electronic device to:
 display, on the touch-sensitive display, a user interface of a first software application; 
 while displaying the user interface of the first software application, detect one or more first touch inputs on a region of the touch-sensitive display that includes the user interface of the first software application; and 
 in response to detecting the one or more first touch inputs:
 in accordance with a determination that the one or more first touch inputs correspond to a system gesture for switching applications, replace display of the user interface of the first software application with display of a user interface of a second software application without delivering information corresponding to the one or more first touch inputs to the first software application, wherein the second software application is different from the first software application; and 
 in accordance with a determination that the one or more first touch inputs do not correspond to a system gesture, deliver the information corresponding to the one or more first touch inputs to the first software application. 
 
 
     
     
       34. The non-transitory computer readable storage medium of  claim 33 , wherein, in accordance with the determination that the one or more first touch inputs do not correspond to a system gesture, the first software application performs an operation in response to the information corresponding to the one or more first touch inputs being delivered to the first software application. 
     
     
       35. The non-transitory computer readable storage medium of  claim 34 , wherein the one or more programs include instructions that, when executed by the electronic device, cause the electronic device to process the one or more first touch inputs using one or more gesture recognizers of the first software application and one or more system gesture recognizers to determine whether the one or more first touch inputs correspond to the system gesture for switching applications. 
     
     
       36. The non-transitory computer readable storage medium of  claim 33 , wherein the one or more programs include instructions that, when executed by the electronic device, cause the electronic device to process the one or more first touch inputs using one or more system gesture recognizers to determine whether the one or more first touch inputs correspond to the system gesture for switching applications. 
     
     
       37. The non-transitory computer readable storage medium of  claim 36 , wherein the one or more system gesture recognizers are associated with an operating system that is different from the first software application. 
     
     
       38. The non-transitory computer readable storage medium of  claim 33 , wherein the one or more programs include instructions that, when executed by the electronic device, cause the electronic device to, prior to detecting the one or more first touch inputs, display the user interface of the first software application without concurrently displaying the user interface of the second software application. 
     
     
       39. The non-transitory computer readable storage medium of  claim 33 , wherein replacing display of the user interface of the first software application with display of the user interface of the second software application includes ceasing to display the user interface of the first software application. 
     
     
       40. The non-transitory computer readable storage medium of  claim 33 , wherein the second software application is a next software application following the first software application in a sequence of applications with retained state information. 
     
     
       41. The non-transitory computer readable storage medium of  claim 33 , wherein the one or more programs include instructions that, when executed by the electronic device, cause the electronic device to:
 while displaying the user interface of the second software application, detect one or more second touch inputs on a region of the touch-sensitive display that includes the user interface of the second software application; and 
 in response to detecting the one or more second touch inputs:
 in accordance with a determination that the one or more second touch inputs correspond to the system gesture for switching applications, replace display of the user interface of the second software application with display of a user interface of a third software application without delivering information corresponding to the one or more second touch inputs to the second software application; and 
 in accordance with a determination that the one or more second touch inputs do not correspond to a system gesture, deliver the information corresponding to the one or more second touch inputs to the second software application. 
 
 
     
     
       42. The non-transitory computer readable storage medium of  claim 41 , wherein the second software application is a next software application following the first software application in a sequence of applications with retained state information, and the third software application is a next software application following the second software application in the sequence of applications with retained state information. 
     
     
       43. The non-transitory computer readable storage medium of  claim 41 , wherein determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs correspond to the system gesture for switching applications performed in a first direction, and wherein:
 in accordance with a determination that the one or more second touch inputs correspond to the system gesture for switching applications performed in the first direction, the third software application is different from the first software application; and 
 in accordance with a determination that the one or more second touch inputs correspond to the system gesture for switching applications performed in a second direction that is opposite the first direction, the third software application is the first software application. 
 
     
     
       44. The non-transitory computer readable storage medium of  claim 43 , wherein:
 the system gesture for switching applications performed in the first direction includes a swipe gesture in the first direction; and 
 the system gesture for switching applications performed in the second direction includes a swipe gesture in the second direction that is opposite the first direction. 
 
     
     
       45. The non-transitory computer readable storage medium of  claim 33 , wherein determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs correspond to a first type of system gesture for switching applications, and the one or more programs include instructions that, when executed by the electronic device, cause the electronic device to:
 in response to detecting the one or more first touch inputs:
 in accordance with a determination that the one or more first touch inputs correspond to a second type of system gesture for switching applications, replace display of at least a portion of the user interface of the first software application with a user interface of an operating system without delivering information corresponding to the one or more first touch inputs to the first software application, wherein the operating system is different from the first software application and from the second software application. 
 
 
     
     
       46. The non-transitory computer readable storage medium of  claim 45 , wherein:
 determining that the one or more first touch inputs correspond to the first type of system gesture for switching applications includes determining that the one or more first touch inputs include a swipe gesture in a first direction; and 
 determining that the one or more first touch inputs correspond to the second type of system gesture for switching applications includes determining that the one or more first touch inputs include a swipe gesture in a second direction that is perpendicular to the first direction. 
 
     
     
       47. The non-transitory computer readable storage medium of  claim 45 , wherein:
 determining that the one or more first touch inputs correspond to the first type of system gesture for switching applications includes determining that the one or more first touch inputs include a swipe gesture; and 
 determining that the one or more first touch inputs correspond to the second type of system gesture for switching applications includes determining that the one or more first touch inputs include a pinch gesture. 
 
     
     
       48. The non-transitory computer readable storage medium of  claim 33 , wherein:
 in accordance with a determination that the electronic device is operating in a first mode:
 determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs match a first gesture definition for the system gesture for switching applications; and 
 
 in accordance with a determination that the electronic device is operating in a second mode:
 determining that the one or more first touch inputs correspond to the system gesture for switching applications includes determining that the one or more first touch inputs match a second gesture definition for the system gesture for switching applications, wherein the second gesture definition is different from the first gesture definition.

Description:
RELATED APPLICATIONS 
     This application is continuation of U.S. patent application Ser. No. 16/898,345, filed Jun. 10, 2020, which is a continuation of U.S. patent application Ser. No. 15/339,768, filed Oct. 31, 2016, now U.S. Pat. No. 10,719,225, which is a continuation application of U.S. patent application Ser. No. 14/043,774, filed Oct. 1, 2013, now U.S. Pat. No. 9,483,121, which is a continuation of U.S. patent application Ser. No. 13/077,927, filed Mar. 31, 2011, now U.S. Pat. No. 8,566,045, which claims priority to U.S. Provisional Application Ser. No. 61/425,222, filed on Dec. 20, 2010, and U.S. application Ser. No. 13/077,927 is a continuation-in-part of: (A) U.S. patent application Ser. No. 12/566,660, filed Sep. 24, 2009, now U.S. Pat. No. 8,285,499, which claims priority to U.S. Provisional Application Ser. No. 61/210,332, filed on Mar. 16, 2009; and (B) U.S. patent application Ser. No. 12/789,695, filed May 28, 2010, now U.S. Pat. No. 9,684,521, entitled “Gesture Recognizers with Delegates for Controlling and Modifying Gesture Recognition,” which claims priority to U.S. Provisional Application Ser. No. 61/298,531, filed Jan. 26, 2010, entitled “Gesture Recognizers with Delegates for Controlling and Modifying Gesture Recognition.” All of these applications are incorporated by reference herein in their entirety. 
     This application relates to U.S. patent application Ser. No. 13/077,524, filed Mar. 31, 2011, now U.S. Pat. No. 9,244,606, entitled “Device, Method, and Graphical User Interface for Navigation of Concurrently Open Software Applications.” This application is incorporated by reference herein in its entirety. 
     This application relates to U.S. patent application Ser. No. 13/077,925, filed Mar. 31, 2011, now U.S. Pat. No. 8,566,044, entitled “Event Recognition,” and U.S. patent application Ser. No. 13/077,931, filed Mar. 31, 2011, now U.S. Pat. No. 9,311,112, entitled “Event Recognition.” Both of these applications are incorporated by reference herein in their entirety. 
    
    
     TECHNICAL FIELD 
     This relates generally to user interface processing, including but not limited to, apparatuses and methods for recognizing touch inputs. 
     BACKGROUND 
     An electronic device typically includes a user interface that is used to interact with the computing device. The user interface may include a display and/or input devices such as a keyboard, mice, and touch-sensitive surfaces for interacting with various aspects of the user interface. In some devices with a touch-sensitive surface as an input device, a first set of touch-based gestures (e.g., two or more of: tap, double tap, horizontal swipe, vertical swipe, pinch, depinch, two finger swipe) are recognized as proper inputs in a particular context (e.g., in a particular mode of a first application), and other, different sets of touch-based gestures are recognized as proper inputs in other contexts (e.g., different applications and/or different modes or contexts within the first application). As a result, the software and logic required for recognizing and responding to touch-based gestures can become complex, and can require revision each time an application is updated or a new application is added to the computing device. These and similar issues may arise in user interfaces that utilize input sources other than touch-based gestures. 
     Thus, it would be desirable to have a comprehensive framework or mechanism for recognizing touch-based gestures and events, as well as gestures and events from other input sources, that is easily adaptable to virtually all contexts or modes of all application programs on a computing device, and that requires little or no revision when an application is updated or a new application is added to the computing device. 
     SUMMARY 
     To address the aforementioned drawbacks, some embodiments provide a method performed at an electronic device with a touch-sensitive display. The electronic device is configured to execute at least a first software application and a second software application. The first software application includes a first set of one or more gesture recognizers, and the second software application includes one or more views and a second set of one or more gesture recognizers. Respective gesture recognizers have corresponding gesture handlers. The method includes displaying at least a subset of the one or more views of the second software application, and while displaying at least the subset of the one or more views of the second software application, detecting a sequence of touch inputs on the touch-sensitive display. The sequence of touch inputs includes a first portion of one or more touch inputs and a second portion of one or more touch inputs subsequent to the first portion. The method also includes, during a first phase of detecting the sequence of touch inputs, delivering the first portion of one or more touch inputs to the first software application and the second software application, identifying from gesture recognizers in the first set one or more matching gesture recognizers that recognize the first portion of one or more touch inputs, and processing the first portion of one or more touch inputs with one or more gesture handlers corresponding to the one or more matching gesture recognizers. 
     In accordance with some embodiments, a method is performed at an electronic device with a touch-sensitive display. The electronic device is configured to execute at least a first software application and a second software application. The first software application includes a first set of one or more gesture recognizers, and the second software application includes one or more views and a second set of one or more gesture recognizers. Respective gesture recognizers have corresponding gesture handlers. The method includes displaying a first set of one or more views. The first set of one or more views includes at least a subset of the one or more views of the second software application. The method also includes, while displaying the first set of the one or more views, detecting a sequence of touch inputs on the touch-sensitive display. The sequence of touch inputs includes a first portion of one or more touch inputs and a second portion of one or more touch inputs subsequent to the first portion. The method includes determining whether at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs. The method also includes, in accordance with a determination that at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs, delivering the sequence of touch inputs to the first software application without delivering the sequence of touch inputs to the second software application, and determining whether at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the sequence of touch inputs. The method furthermore includes, in accordance with a determination that at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the sequence of touch inputs, processing the sequence of touch inputs with the at least one gesture recognizer in the first set of one or more gesture recognizers that recognizes the sequence of touch inputs. The method also includes, in accordance with a determination that no gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs, delivering the sequence of touch inputs to the second software application, and determining whether at least one gesture recognizer in the second set of one or more gesture recognizers recognizes the sequence of touch inputs. The method furthermore includes, in accordance with a determination that at least one gesture recognizer in the second set of one or more gesture recognizers recognizes the sequence of touch inputs, processing the sequence of touch inputs with the at least one gesture recognizer in the second set of one or more gesture recognizers that recognizes the sequence of touch inputs. 
     In accordance with some embodiments, a method is performed at an electronic device with an internal state. The electronic device is configured to execute software that includes a view hierarchy with a plurality of views. The method includes displaying one or more views of the view hierarchy, and executing one or more software elements. Each software element is associated with a particular view, and each particular view includes one or more event recognizers. Each event recognizer has one or more event definitions based on one or more sub-events, and an event handler, which specifies an action for a target, and is configured to send the action to the target in response to the event recognizer detecting an event corresponding to a particular event definition of the one or more event definitions. The method also includes detecting a sequence of one or more sub-events, and identifying one of the views of the view hierarchy as a hit view. The hit view establishes which views in the view hierarchy are actively involved views. The method furthermore includes delivering a respective sub-event to event recognizers for each actively involved view within the view hierarchy. At least one event recognizer for actively involved views in the view hierarchy has a plurality of event definitions, and one in the plurality of event definitions is selected in accordance with the internal state of the electronic device. The at least one event recognizer processes the respective sub-event prior to processing a next sub-event in the sequence of sub-events in accordance with the selected event definition. 
     In accordance with some embodiments, a non-transitory computer readable storage medium stores one or more programs for execution by one of more processors of an electronic device. The one or more programs include one or more instructions, which when executed by the electronic device, cause the device to perform any of the methods described above. 
     In accordance with some embodiments, an electronic device with a touch-sensitive display includes one or more processors, and memory storing one or more programs for execution by the one or more processors. The one or more programs include instructions for implementing any of the methods described above. 
     In accordance with some embodiments, an electronic device with a touch-sensitive display includes means for implementing any of the methods described above. 
     In accordance with some embodiments, an information processing apparatus in a multifunction device with a touch-sensitive display includes means for implementing any of the methods described above. 
     In accordance with some embodiments, an electronic device includes a touch-sensitive display unit configured to receive touch inputs, and a processing unit coupled to the touch-sensitive display unit. The processing unit is configured to execute at least a first software application and a second software application. The first software application includes a first set of one or more gesture recognizers, and the second software application includes one or more views and a second set of one or more gesture recognizers. Respective gesture recognizers have corresponding gesture handlers. The processing unit is configured to: enable display of at least a subset of the one or more views of the second software application; and while displaying at least the subset of the one or more views of the second software application, detect a sequence of touch inputs on the touch-sensitive display unit. The sequence of touch inputs includes a first portion of one or more touch inputs and a second portion of one or more touch inputs subsequent to the first portion. The processing unit is configured to, during a first phase of detecting the sequence of touch inputs: deliver the first portion of one or more touch inputs to the first software application and the second software application; identify from gesture recognizers in the first set one or more matching gesture recognizers that recognize the first portion of one or more touch inputs; and process the first portion of one or more touch inputs with one or more gesture handlers corresponding to the one or more matching gesture recognizers. 
     In accordance with some embodiments, an electronic device includes a touch-sensitive display unit configured to receive touch inputs, and a processing unit coupled to the touch-sensitive display unit. The processing unit is configured to execute at least a first software application and a second software application. The first software application includes a first set of one or more gesture recognizers, and the second software application includes one or more views and a second set of one or more gesture recognizers. Respective gesture recognizers have corresponding gesture handlers. The processing unit is configured to enable display of a first set of one or more views. The first set of one or more views includes at least a subset of the one or more views of the second software application. The processing unit is configured to, while displaying the first set of the one or more views: detect a sequence of touch inputs on the touch-sensitive display unit (the sequence of touch inputs includes a first portion of one or more touch inputs and a second portion of one or more touch inputs subsequent to the first portion); and determine whether at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs. The processing unit is configured to, in accordance with a determination that at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs: deliver the sequence of touch inputs to the first software application without delivering the sequence of touch inputs to the second software application; and determine whether at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the sequence of touch inputs. The processing unit is configured to, in accordance with a determination that at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the sequence of touch inputs, process the sequence of touch inputs with the at least one gesture recognizer in the first set of one or more gesture recognizers that recognizes the sequence of touch inputs. The processing unit is configured to, in accordance with a determination that no gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs: deliver the sequence of touch inputs to the second software application; determine whether at least one gesture recognizer in the second set of one or more gesture recognizers recognizes the sequence of touch inputs; and in accordance with a determination that at least one gesture recognizer in the second set of one or more gesture recognizers recognizes the sequence of touch inputs, process the sequence of touch inputs with the at least one gesture recognizer in the second set of one or more gesture recognizers that recognizes the sequence of touch inputs. 
     In accordance with some embodiments, an electronic device includes: a display unit configured to display one or more views; a memory unit configured to store an internal state; and a processing unit coupled to the display unit and the memory unit. The processing unit is configured to: execute software that includes a view hierarchy with a plurality of views; enable display of one or more views of the view hierarchy; and execute one or more software elements. Each software element is associated with a particular view, and each particular view includes one or more event recognizers. Each event recognizer has: one or more event definitions based on one or more sub-events, and an event handler. The event handler specifies an action for a target, and is configured to send the action to the target in response to the event recognizer detecting an event corresponding to a particular event definition of the one or more event definitions. The processing unit is configured to: detect a sequence of one or more sub-events; and identify one of the views of the view hierarchy as a hit view. The hit view establishes which views in the view hierarchy are actively involved views. The processing unit is configured to deliver a respective sub-event to event recognizers for each actively involved view within the view hierarchy. At least one event recognizer for actively involved views in the view hierarchy has a plurality of event definitions, one of which is selected in accordance with the internal state of the electronic device, and the at least one event recognizer processes the respective sub-event prior to processing a next sub-event in the sequence of sub-events in accordance with the selected event definition. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 A- 1 C  are block diagrams illustrating electronic devices in accordance with some embodiments. 
         FIG.  2    is a diagram of an input/output processing stack of an exemplary electronic device in accordance with some embodiments. 
         FIG.  3 A  illustrates an exemplary view hierarchy in accordance with some embodiments. 
         FIGS.  3 B and  3 C  are block diagrams illustrating exemplary event recognizer methods and data structures in accordance with some embodiments. 
         FIG.  3 D  is a block diagram illustrating exemplary components for event handling in accordance with some embodiments. 
         FIG.  3 E  is a block diagram illustrating exemplary classes and instances of gesture recognizers in accordance with some embodiments. 
         FIG.  3 F  is a block diagram illustrating the flow of event information in accordance with some embodiments. 
         FIGS.  4 A and  4 B  are flow charts illustrating exemplary state machines in accordance with some embodiments. 
         FIG.  4 C  illustrates the exemplary state machines of  FIGS.  4 A and  4 B  to an exemplary set of sub-events in accordance with some embodiments. 
         FIGS.  5 A- 5 C  illustrate exemplary sub-event sequences with exemplary event recognizer state machines in accordance with some embodiments. 
         FIGS.  6 A and  6 B  are event recognition method flow diagrams in accordance with some embodiments. 
         FIGS.  7 A- 7 S  illustrate exemplary user interfaces and user inputs recognized by event recognizers for navigating through concurrently open applications in accordance with some embodiments. 
         FIGS.  8 A and  8 B  are flow diagrams illustrating an event recognition method in accordance with some embodiments. 
         FIGS.  9 A- 9 C  are flow diagrams illustrating an event recognition method in accordance with some embodiments. 
         FIGS.  10 A- 10 B  are flow diagrams illustrating an event recognition method in accordance with some embodiments. 
         FIG.  11    is a functional block diagram of an electronic device in accordance with some embodiments. 
         FIG.  12    is a functional block diagram of an electronic device in accordance with some embodiments. 
         FIG.  13    is a functional block diagram of an electronic device in accordance with some embodiments. 
     
    
    
     Like reference numerals refer to corresponding parts throughout the drawings. 
     DESCRIPTION OF EMBODIMENTS 
     Electronic devices with small screens (e.g., smart phones and tablets) typically display a single application at a time, even though multiple applications may be running on the device. Many of these devices have touch-sensitive displays configured to receive gesture as touch inputs. With such devices, a user may want to perform operations that are provided by a hidden application (e.g., an application that is running in the background and is not currently displayed on the display of the electronic device, such as an application launcher software application running in the background). Existing methods for performing operations provided by a hidden application typically require first displaying the hidden application and then providing touch inputs to the now displayed application. Therefore, the existing methods require additional steps. Furthermore, the user may not want to see the hidden application, but yet still want to perform an operation provided by the hidden application. In the embodiments described below, improved methods for interacting with a hidden application is achieved by delivering touch inputs to the hidden application, and processing the touch inputs with the hidden application without displaying the hidden application. Thus, these methods streamline the interaction with a hidden application, thereby eliminating the need for extra, separate steps to display the hidden application, while providing the ability to control and interact with the hidden application based on a gesture input. 
     In addition, in some embodiments, such electronic devices have at least one gesture recognizer with a plurality of gesture definitions. This helps the gesture recognizer work in different distinct operating modes. For example, a device may have a normal operating mode and an accessibility operating mode (e.g., for people with limited vision). In the normal operating mode, a next application gesture is used to move between applications, and the next application gesture is defined as a three-finger left-swipe gesture. In the accessibility operating mode, the three-finger left-swipe gesture is used to perform a different function. Thus, a gesture different from the three-finger left-swipe is needed in the accessibility operating mode to correspond to the next application gesture (e.g., a four-finger left-swipe gesture in the accessibility operating mode). By having multiple gesture definitions associated with the next application gesture, the device can select one of the gesture definitions for the next application gesture, depending on the current operating mode. This provides flexibility in using the gesture recognizer in different operating modes. In some embodiments, a plurality of gesture recognizers with multiple gesture definitions is adjusted depending on the operating mode (e.g., gestures performed with three fingers in the normal operating mode are performed with four fingers in the accessibility operating mode). 
     Below,  FIGS.  1 A- 1 C and  2    provide a description of exemplary devices.  FIGS.  3 A- 3 F  describe components for event handling and the operation (e.g., flow of event information) of such components.  FIGS.  4 A- 4 C and  5 A- 5 C  describe operations of event recognizers in more detail.  FIGS.  6 A- 6 B  are flow diagrams illustrating event recognition methods.  FIGS.  7 A- 7 S  are exemplary user interfaces illustrating operations using event recognition methods in  FIGS.  8 A- 8 B,  9 A- 9 C, and  10   .  FIGS.  8 A- 8 B  are flow diagrams illustrating an event recognition method of processing the event information with a gesture handler of a hidden open application.  FIGS.  9 A- 9 C  are flow diagrams illustrating an event recognition method of conditionally processing the event information with a gesture recognizer of a hidden open application or a displayed application.  FIG.  10    is a flow diagram illustrating an event recognition method of selecting an event definition of a plurality of event definitions for a single event recognizer. 
     Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits, and networks have not been described in detail so as not to unnecessarily obscure aspects of the embodiments. 
     It will also be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first contact could be termed a second contact, and, similarly, a second contact could be termed a first contact, without departing from the scope of the present invention. The first contact and the second contact are both contacts, but they are not the same contact. 
     The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the description of the invention and the appended claims, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     As used herein, the term “if” may be construed to mean “when” or “upon” or “in response to determining” or “in response to detecting,” depending on the context. Similarly, the phrase “if it is determined” or “if [a stated condition or event] is detected” may be construed to mean “upon determining” or “in response to determining” or “upon detecting (the stated condition or event)” or “in response to detecting (the stated condition or event),” depending on the context. 
     As used herein, the term “event” refers to an input detected by one or more sensors of the device. In particular, the term “event” includes a touch on a touch-sensitive surface. An event comprises one or more sub-events. Sub-events typically refer to changes to an event (e.g., a touch-down, touch-move, and lift-off of the touch can be sub-events). Sub-events in the sequence of one or more sub-events can include many forms, including without limitation, key presses, key press holds, key press releases, button presses, button press holds, button press releases, joystick movements, mouse movements, mouse button presses, mouse button releases, pen stylus touches, pen stylus movements, pen stylus releases, oral instructions, detected eye movements, biometric inputs, and detected physiological changes in a user, among others. Since an event may comprise a single sub-event (e.g., a short lateral motion of the device), the term “sub-event” as used herein also refers to an event. 
     As used herein, the terms “event recognizer” and “gesture recognizer” are used interchangeably to refer to a recognizer that can recognize a gesture or other events (e.g., motion of the device). As used herein, the terms “event handler” and “gesture handler” are used interchangeably to refer to a handler that performs a predefined set of operations (e.g., updating data, updating object(s), and/or updating display) in response to recognition of an event/sub-event or a gesture. 
     As noted above, in some devices with a touch-sensitive surface as an input device, a first set of touch-based gestures (e.g., two or more of: tap, double tap, horizontal swipe, vertical swipe) are recognized as proper inputs in a particular context (e.g., in a particular mode of a first application), and other, different sets of touch-based gestures are recognized as proper inputs in other contexts (e.g., different applications and/or different modes or contexts within the first application). As a result, the software and logic required for recognizing and responding to touch-based gestures can become complex, and can require revision each time an application is updated or a new application is added to the computing device. Embodiments described herein address these problems by providing a comprehensive framework for handling events and/or gesture inputs. 
     In the embodiments described below, touch-based gestures are events. Upon recognition of a predefined event, e.g., an event that corresponds to a proper input in the current context of an application, information concerning the event is delivered to the application. Furthermore, each respective event is defined as a sequence of sub-events. In devices that have a multi-touch display device (often herein called “screens”) or other multi-touch sensitive surface, and that accept multi-touch-based gestures, the sub-events that define a multi-touched based event may include multi-touch sub-events (requiring two or more fingers to be simultaneously in contact with the device&#39;s touch-sensitive surface). For example, in a device having a multi-touch sensitive display, a respective multi-touch sequence of sub-events may begin when a user&#39;s finger first touches the screen. Additional sub-events may occur when one or more additional fingers subsequently or concurrently touch the screen, and yet other sub-events may occur when all of the fingers touching the screen move across the screen. The sequence ends when the last of the user&#39;s fingers is lifted from the screen. 
     When using touch-based gestures to control an application running in a device having a touch-sensitive surface, touches have both temporal and spatial aspects. The temporal aspect, called a phase, indicates when a touch has just begun, whether it is moving or stationary, and when it ends—that is, when the finger is lifted from the screen. A spatial aspect of a touch is the set of views or user interface windows in which the touch occurs. The views or windows in which a touch is detected may correspond to programmatic levels within a programmatic or view hierarchy. For example, the lowest level view in which a touch is detected may be called the hit view, and the set of events that are recognized as proper inputs may be determined based, at least in part, on the hit view of the initial touch that begins a touch-based gesture. Alternatively, or additionally, events are recognized as proper inputs based, at least in part, on one or more software programs (i.e., software applications) in the programmatic hierarchy. For example, a five-finger pinch gesture is recognized as a proper input in an application launcher that has a five-finger pinch gesture recognizer, but not in a web browser application that does not have the five-finger pinch gesture recognizer. 
       FIGS.  1 A- 1 C  are block diagrams illustrating different embodiments of electronic device  102 , in accordance with some embodiments. Electronic device  102  may be any electronic device including, but not limited to, a desktop computer system, a laptop computer system, a mobile phone, a smart phone, a personal digital assistant, or a navigation system. Electronic device  102  may also be a portable electronic device with a touch screen display (e.g., touch-sensitive display  156 ,  FIG.  1 B ) configured to present a user interface, a computer with a touch screen display configured to present a user interface, a computer with a touch sensitive surface and a display configured to present a user interface, or any other form of computing device, including without limitation, consumer electronic devices, mobile telephones, video game systems, electronic music players, tablet PCs, electronic book reading systems, e-books, PDAs, electronic organizers, email devices, laptops or other computers, kiosk computers, vending machines, smart appliances, etc. Electronic device  102  includes user interface  113 . 
     In some embodiments, electronic device  102  includes a touch-sensitive display  156  ( FIG.  1 B ). In these embodiments, user interface  113  may include an on-screen keyboard (not depicted) that is used by a user to interact with electronic device  102 . In some embodiments, electronic device  102  also includes one or more input devices  128  (e.g., keyboard, mouse, trackball, microphone, physical button(s), touchpad, etc.). In some embodiments, touch-sensitive display  156  has the ability to detect two or more distinct, concurrent (or partially concurrent) touches, and in these embodiments, display  156  is sometimes herein called a multitouch display or multitouch-sensitive display. In some embodiments, a keyboard of the one or more input devices  128  may be separate and distinct from electronic device  102 . For example, a keyboard may be a wired or wireless keyboard coupled to electronic device  102 . 
     In some embodiments, electronic device  102  includes display  126  and one or more input devices  128  (e.g., keyboard, mouse, trackball, microphone, physical button(s), touchpad, trackpad, etc.) that are coupled to electronic device  102 . In these embodiments, one or more of input devices  128  may optionally be separate and distinct from electronic device  102 . For example, the one or more input devices may include one or more of: a keyboard, a mouse, a trackpad, a trackball, and an electronic pen, any of which may optionally be separate from the electronic device. Optionally, device  102  may include one or more sensors  116 , such as one or more accelerometers, gyroscopes, GPS systems, speakers, infrared (IR) sensors, biometric sensors, cameras, etc. It is noted that the description above of various exemplary devices as input devices  128  or as sensors  116  is of no significance to the operation of the embodiments described herein, and that any input or sensor device described herein as an input device may equally well be described as a sensor, and vice versa. In some embodiments, signals produced by one or more sensors  116  are used as input sources for detecting events. 
     In some embodiments, electronic device  102  includes touch-sensitive display  156  (i.e., a display having a touch-sensitive surface) and one or more input devices  128  that are coupled to electronic device  102  ( FIG.  1 B ). In some embodiments, touch-sensitive display  156  has the ability to detect two or more distinct, concurrent (or partially concurrent) touches, and in these embodiments, display  156  is sometimes herein called a multitouch display or multitouch-sensitive display. 
     In some embodiments of electronic device  102  discussed herein, input devices  128  are disposed in electronic device  102 . In other embodiments, one or more of input devices  128  is separate and distinct from electronic device  102 . For example, one or more of input devices  128  may be coupled to electronic device  102  by a cable (e.g., USB cable) or wireless connection (e.g., Bluetooth connection). 
     When using input devices  128 , or when performing a touch-based gesture on touch-sensitive display  156  of electronic device  102 , the user generates a sequence of sub-events that are processed by one or more CPUs  110  of electronic device  102 . In some embodiments, one or more CPUs  110  of the electronic device  102  process the sequence of sub-events to recognize events. 
     Electronic device  102  typically includes one or more single- or multi-core processing units (“CPU” or “CPUs”)  110  as well as one or more network or other communications interfaces  112 . Electronic device  102  includes memory  111  and one or more communication buses  115  for interconnecting these components. Communication buses  115  may include circuitry (sometimes called a chipset) that interconnects and controls communications between system components (not depicted herein). As discussed above, electronic device  102  includes user interfaces  113  including a display (e.g., display  126  or touch-sensitive display  156 ). Further, electronic device  102  typically includes input devices  128  (e.g., keyboard, mouse, touch sensitive surfaces, keypads, etc.). In some embodiments, the input devices  128  include an on-screen input device (e.g., a touch-sensitive surface of a display device). Memory  111  may include high-speed random access memory, such as DRAM, SRAM, DDR RAM or other random access solid state memory devices; and may include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices. Memory  111  may optionally include one or more storage devices remotely located from the CPU(s)  110 . Memory  111 , or alternately the non-volatile memory device(s) within memory  111 , comprise a computer readable storage medium. In some embodiments, memory  111 , or the non-volatile memory device(s) within memory  111 , comprises a non-transitory computer readable storage medium. In some embodiments, memory  111  (of electronic device  102 ) or the computer readable storage medium of memory  111  stores the following programs, modules and data structures, or a subset thereof:
         operating system  118 , which includes procedures for handling various basic system services and for performing hardware dependent tasks;   accessibility module  127  ( FIG.  1 C ), which is used for modifying behavior of one or more software applications in application software  124  or modifying data from touch-sensitive display  156  or input device(s)  128  to improve accessibility of the one or more software applications in application software  124  or accessibility to content (e.g., a web page) displayed therein (e.g., for people with impaired vision or limited motion capabilities);   communication module  120 , which is used for connecting electronic device  102  to other devices via one or more respective communication interfaces  112  (wired or wireless) and one or more communication networks, such as the Internet, other wide area networks, local area networks, metropolitan area networks, and so on;   user interface module  123  ( FIG.  1 C ), which is used for displaying user interfaces including user interface objects on display  126  or touch-sensitive display  156 ;   control application  132  ( FIG.  1 C ), which is used for controlling processes (e.g., hit view determination, thread management, and/or event monitoring, etc.); in some embodiments, control application  132  includes a run-time application; in other embodiments, the run-time application includes control application  132 ;   event delivery system  122 , which may be implemented in various alternate embodiments within operating system  118  or in application software  124 ; in some embodiments, however, some aspects of event delivery system  122  may be implemented in operating system  118  while other aspects are implemented in application software  124 ;   application software  124 , which includes one or more software applications (e.g., applications  133 - 1 ,  133 - 2 , and  133 - 3  in  FIG.  1 C , each of which can be one of: an email application, a web browser application, a notes application, a text messaging application, etc.); a respective software application typically has, at least during execution, an application state, indicating the state of the respective software application and its components (e.g., gesture recognizers); see application internal state  321  ( FIG.  3 D ) described below; and   device/global internal state  134  ( FIG.  1 C ), which includes one or more of: application state, indicating the state of software applications and their components (e.g., gesture recognizers and delegates); display state, indicating what applications, views or other information occupy various regions of touch-sensitive display  156  or display  126 ; sensor state, including information obtained from the device&#39;s various sensors  116 , input devices  128 , and/or touch-sensitive display  156 ; location information concerning the device&#39;s location and/or attitude; and other states.       

     As used in the specification and claims, the term “open application” refers to a software application with retained state information (e.g., as part of device/global internal state  134  and/or application internal state  321  ( FIG.  3 D )). An open application is any one of the following types of applications:
         an active application, which is currently displayed on display  126  or touch-sensitive display  156  (or a corresponding application view is currently displayed on the display);   a background application (or background process), which is not currently displayed on display  126  or touch-sensitive display  156 , but one or more application processes (e.g., instructions) for the corresponding application are being processed by one or more processors  110  (i.e., running);   a suspended application, which is not currently running, and the application is stored in a volatile memory (e.g., DRAM, SRAM, DDR RAM, or other volatile random access solid state memory device of memory  111 ); and   a hibernated application, which is not running, and the application is stored in a non-volatile memory (e.g., one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices of memory  111 ).       

     As used herein, the term “closed application” refers to software applications without retained state information (e.g., state information for closed applications is not stored in a memory of the device). Accordingly, closing an application includes stopping and/or removing application processes for the application and removing state information for the application from the memory of the device. Generally, opening a second application while in a first application does not close the first application. When the second application is displayed and the first application ceases to be displayed, the first application, which was an active application when displayed, may become a background application, suspended application, or hibernated application, but the first application remains an open application while its state information is retained by the device. 
     Each of the above identified elements may be stored in one or more of the previously mentioned memory devices. Each of the above identified module, application or system elements corresponds to a set of instructions for performing functions described herein. The set of instructions can be executed by one or more processors (e.g., one or more CPUs  110 ). The above identified modules or programs (i.e., sets of instructions) need not be implemented as separate software programs, procedures or modules, and thus various subsets of these modules may be combined or otherwise rearranged in various embodiments. In some embodiments, memory  111  may store a subset of the modules and data structures identified above. Furthermore, memory  111  may store additional modules and data structures not described above. 
       FIG.  2    is a diagram of input/output processing stack  200  of an exemplary electronic device or apparatus (e.g., device  102 ) according to some embodiments of the invention. Hardware (e.g., electronic circuitry)  212  of the device is at the base level of the input/output processing stack  200 . Hardware  212  can include various hardware interface components, such as the components depicted in  FIGS.  1 A and/or  1 B . Hardware  212  can also include one or more of above mentioned sensors  116 . At least some of the other elements ( 202 - 210 ) of input/output processing stack  200  are software procedures, or portions of software procedures, that process inputs received from hardware  212  and generate various outputs that are presented through a hardware user interface (e.g., one or more of a display, speakers, device vibration actuator, etc.). 
     A driver or a set of drivers  210  communicates with hardware  212 . Drivers  210  can receive and process input data received from hardware  212 . Core Operating System (“OS”)  208  can communicate with driver(s)  210 . Core OS  208  can process raw input data received from driver(s)  210 . In some embodiments, drivers  210  can be considered to be a part of core OS  208 . 
     A set of OS application programming interfaces (“OS APIs”)  206 , are software procedures that communicate with core OS  208 . In some embodiments, APIs  206  are included in the device&#39;s operating system, but at a level above core OS  208 . APIs  206  are designed for use by applications running on the electronic devices or apparatuses discussed herein. User interface (UI) APIs  204  can utilize OS APIs  206 . Application software (“applications”)  202  running on the device can utilize UI APIs  204  in order to communicate with the user. UI APIs  204  can, in turn, communicate with lower level elements, ultimately communicating with various user interface hardware, e.g., multitouch display  156 . In some embodiments, application software  202  includes applications in application software  124  ( FIG.  1 A ). 
     While each layer input/output processing stack  200  can utilize the layer underneath it, that is not always required. For example, in some embodiments, applications  202  may directly communicate with OS APIs  206 . In general, layers at or above OS API layer  206  may not directly access Core OS  208 , driver(s)  210 , or hardware  212 , as these layers are considered private. Applications in layer  202  and UI API  204  usually direct calls to the OS API  206 , which in turn, accesses the layers Core OS  208 , driver(s)  210 , and hardware  212 . 
     Stated in another way, one or more hardware elements  212  of electronic device  102 , and software running on the device detect input events (which may correspond to sub-events in a gesture) at one or more of the input device(s)  128  and/or a touch-sensitive display  156  and generate or update various data structures (stored in memory  111  of device  102 ) used by a set of currently active event recognizers to determine whether and when the input events correspond to an event to be delivered to application software  124 . Embodiments of event recognition methodologies, apparatus and computer program products are described in more detail below. 
       FIG.  3 A  depicts an exemplary view hierarchy  300 , which in this example is a search program displayed in outermost view  302 . Outermost view  302  generally encompasses the entire user interface a user may directly interact with, and includes subordinate views, e.g.,
         search results panel  304 , which groups search results and can be scrolled vertically;   search field  306 , which accepts text inputs; and   a home row  310 , which groups applications for quick access.       

     In this example, each subordinate view includes lower-level subordinate views. In other examples, the number of view levels in the hierarchy  300  may differ in different branches of the hierarchy, with one or more subordinate views having lower-level subordinate views, and one or more other subordinate views not have any such lower-level subordinate views. Continuing with the example shown in  FIG.  3 A , search results panel  304  contains separate subordinate views  305  (subordinate to panel  304 ) for each search result. Here, this example shows one search result in a subordinate view called the maps view  305 . Search field  306  includes a subordinate view herein called clear contents icon view  307 , which clears the contents of the search field when a user performs a particular action (e.g., a single touch or tap gesture) on the clear contents icon in view  307 . Home row  310  includes subordinate views  310 - 1 ,  310 - 2 ,  310 - 3 , and  310 - 4 , which respectively correspond to a contacts application, an email application, a web browser, and an iPod music interface. 
     A touch sub-event  301 - 1  is represented in outermost view  302 . Given the location of touch sub-event  301 - 1  over both the search results panel  304 , and maps view  305 , the touch sub-event is also represented over those views as  301 - 2  and  301 - 3 , respectively. Actively involved views of the touch sub-event include the views search results panel  304 , maps view  305  and outermost view  302 . Additional information regarding sub-event delivery and actively involved views is provided below with reference to  FIGS.  3 B and  3 C . 
     Views (and corresponding programmatic levels) can be nested. In other words, a view can include other views. Consequently, the software element(s) (e.g., event recognizers) associated with a first view can include or be linked to one or more software elements associated with views within the first view. While some views can be associated with applications, others can be associated with high level OS elements, such as graphical user interfaces, window managers, etc. In some embodiments, some views are associated with other OS elements. In some embodiments, the view hierarchy includes views from a plurality of software applications. For example, the view hierarchy may include a view from an application launcher (e.g., a home screen) and a view from a web browser application (e.g., a view including content of a web page). 
     A programmatic hierarchy includes one or more software elements or software applications in a hierarchy. To simplify subsequent discussion, reference will generally be made only to views and the view hierarchy, but it must be understood that in some embodiments, the method may operate with a programmatic hierarchy with a plurality of programmatic layers, and/or a view hierarchy. 
       FIGS.  3 B and  3 C  depict exemplary methods and structures related to event recognizers.  FIG.  3 B  depicts methods and data structures for event handling when event handlers are associated with particular views within a hierarchy of views.  FIG.  3 C  depicts methods and data structures for event handling when event handlers are associated with particular levels within a hierarchy of programmatic levels. Event recognizer global methods  312  and  350  include hit view and hit level determination modules  314  and  352 , respectively, active event recognizer determination modules  316  and  354 , and sub-event delivery modules  318  and  356 . 
     In some embodiments, electronic device  102  includes one or more of: event recognizer global methods  312  and  350 . In some embodiments, electronic device  102  includes one or more of: hit view determination module  314  and hit level determination module  352 . In some embodiments, electronic device  102  includes one or more of: active event recognizer determination modules  316  and  354 . In some embodiments, electronic device  102  includes one or more of: sub-event delivery modules  318  and  356 . In some embodiments, one or more of these methods and modules are included in fewer or more methods and modules. For example, in some embodiments, electronic device  102  includes a hit view/level determination module which includes the functionality of hit view determination module  314  and hit level determination module  352 . In some embodiments, electronic device  102  includes an active event recognizer determination module which includes the functionality of active event recognizer determination modules  316  and  354 . 
     Hit view and hit level determination modules,  314  and  352 , respectively, provide software procedures for determining where a sub-event has taken place within one or more views (e.g., the exemplary view hierarchy  300  depicted in  FIG.  3 A , which has three main branches) and/or one or more software elements in the programmatic hierarchy that correspond to the sub-event (e.g., one or more of applications  133  in  FIG.  1 C ). 
     The hit view determination module  314  of  FIG.  3 B , receives information related to a sub-event, e.g., a user touch represented as  301 - 1  on the outermost view  302 , on a search result (maps view  305 ) and the search results panel view  304 . The hit view determination module  314  identifies a hit-view as the lowest view in the hierarchy which should handle the sub-event. In most circumstances, the hit view is the lowest level view in which an initiating sub-event (i.e., the first sub-event in the sequence of sub-events that form an event or potential event) occurs. In some embodiments, once the hit-view is identified, it will receive all sub-events related to the same touch or input source for which the hit view was identified. In some embodiments, one or more other views (e.g., a default or predefined view) receive at least some of the sub-events that the hit view receives. 
     In some embodiments, the hit level determination module  352  of  FIG.  3 C  may utilize an analogous process. For example, in some embodiments, the hit level determination module  352  identifies a hit level as the lowest level in the programmatic hierarchy (or a software application in the lowest programmatic level in the programmatic hierarchy) which should handle the sub-event. In some embodiments, once the hit level is identified, it or a software application in the hit level will receive all sub-events related to the same touch or input source for which the hit level was identified. In some embodiments, one or more other levels or software applications (e.g., a default or predefined software application) receive at least some of the sub-events that the hit view receives. 
     Active event recognizer determination modules  316  and  354  of event recognizer global methods  312  and  350 , respectively, determine which view or views within a view hierarchy and/or a programmatic hierarchy should receive a particular sequence of sub-events.  FIG.  3 A  depicts an exemplary set of active views,  302 ,  304  and  305 , that receive the sub-event  301 . In the example of  FIG.  3 A , the active event recognizer determination module  316  would determine that the outermost view  302 , search results panel  304  and maps view  305  are actively involved views because these views include the physical location of the touch represented by sub-event  301 . It is noted that even if touch sub-event  301  were entirely confined to the area associated with maps view  305 , search results panel  304  and outermost view  302  would still remain in the actively involved views since the search results panel  304  and outermost view  302  are ancestors of maps view  305 . 
     In some embodiments, active event recognizer determination modules  316  and  354  utilize analogous processes. In the example of  FIG.  3 A , the active event recognizer determination module  350  would determine that the map application is actively involved because the views of the map application are displayed and/or the views of the map application include the physical location of the touch represented by sub-event  301 . It is noted that even if touch sub-event  301  were entirely confined to the area associated with the map application, other applications in the programmatic hierarchy may still remain as actively involved applications (or applications in the actively involved programmatic levels). 
     Sub-event delivery module  318  delivers sub-events to event recognizers for actively involved views. Using the example of  FIG.  3 A , a user&#39;s touch is represented in different views of the hierarchy by touch marks  301 - 1 ,  301 - 2 , and  301 - 3 . In some embodiments, sub-event data representing this user&#39;s touch is delivered by the sub-event delivery module  318  to event recognizers at the actively involved views, i.e., top level view  302 , search results panel  304  and maps view  305 . Further, the event recognizers of a view can receive subsequent sub-events of an event that starts within the view (e.g., when an initial sub-event occurs within the view). Stated in another way, a view can receive sub-events associated with user interactions beginning in the view, even if it continues outside of the view. 
     In some embodiments, sub-event delivery module  356  delivers sub-events to event recognizers for actively involved programmatic levels in a process analogous to that used by sub-event delivery module  318 . For example, sub-event delivery module  356  delivers sub-events to event recognizers for actively involved applications. Using the example of  FIG.  3 A , a user&#39;s touch  301  is delivered by sub-event delivery module  356  to event recognizers at the actively involved views (e.g., the map application and any other actively involved applications in the programmatic hierarchy). In some embodiments, a default or predefined software application is included in the programmatic hierarchy by default. 
     In some embodiments, a separate event recognizer structure  320  or  360  is generated and stored in memory of the device for each actively involved event recognizer. Event recognizer structures  320  and  360  typically include an event recognizer state  334 ,  374 , respectively (discussed in greater detail below when referring to  FIGS.  4 A and  4 B ), and event recognizer specific code  338 ,  378 , respectively, having state machines  340 ,  380 , respectively. Event recognizer structure  320  also includes a view hierarchy reference  336 , while event recognizer structure  360  includes a programmatic hierarchy reference  376 . Each instance of a particular event recognizer references exactly one view or programmatic level. View hierarchy reference  336  or programmatic hierarchy reference  376  (for a particular event recognizer) is used to establish which view or programmatic level is logically coupled to the respective event recognizer. 
     View metadata  341  and level metadata  381  may include data regarding a view or level, respectively. View or level metadata may include at least the following properties that may influence sub-event delivery to event recognizers:
         A stop property  342 ,  382 , which, when set for a view or programmatic level prevents sub-event delivery to event recognizers associated with the view or programmatic level as well as its ancestors in the view or programmatic hierarchy.   A skip property  343 ,  383 , which, when set for a view or programmatic level prevents sub-event delivery to event recognizers associated with that view or programmatic level, but permits sub-event delivery to its ancestors in the view or programmatic hierarchy.   A NoHit skip property  344 ,  384 , which, when set for a view, prevents delivery of sub-events to event recognizers associated with the view unless the view is the hit view. As discussed above, the hit view determination module  314  identifies a hit-view (or hit level in the case of hit level determination module  352 ) as the lowest view in the hierarchy which should handle the sub-event.       

     Event recognizer structures  320  and  360  may include metadata  322 ,  362 , respectively. In some embodiments, the metadata  322 ,  362  includes configurable properties, flags, and lists that indicate how the event delivery system should perform sub-event delivery to actively involved event recognizers. In some embodiments, metadata  322 ,  362  may include configurable properties, flags, and lists that indicate how event recognizers may interact with one another. In some embodiments, metadata  322 ,  362  may include configurable properties, flags, and lists that indicate whether sub-events are delivered to varying levels in the view or programmatic hierarchy. In some embodiments, the combination of event recognizer metadata  322 ,  362  and view or level metadata ( 341 ,  381 , respectively) are both be used to configure the event delivery system to: a) perform sub-event delivery to actively involved event recognizers, b) indicate how event recognizers may interact with one another, and c) indicate whether and when sub-events are delivered to various levels in the view or programmatic hierarchy. 
     It is noted that, in some embodiments, a respective event recognizer sends an event recognition action  333 ,  373  to its respective target  335 ,  375 , as specified by fields of the event recognizer&#39;s structure  320 ,  360 . Sending an action to a target is distinct from sending (and deferred sending) sub-events to a respective hit view or level. 
     The metadata properties stored in a respective event recognizer structure  320 ,  360  of a corresponding event recognizer includes one or more of:
         An exclusivity flag  324 ,  364 , which, when set for an event recognizer, indicates that upon recognition of an event by the event recognizer, the event delivery system should stop delivering sub-events to any other event recognizers of the actively involved views or programmatic levels (with the exception of any other event recognizers listed in an exception list  326 ,  366 ). When receipt of a sub-event causes a particular event recognizer to enter the exclusive state, as indicated by its corresponding exclusivity flag  324  or  364 , then subsequent sub-events are delivered only to the event recognizer in the exclusive state (as well as any other event recognizers listed in an exception list  326 ,  366 ).   Some event recognizer structures  320 ,  360 , may include an exclusivity exception list  326 ,  366 . When included in the event recognizer structure  320 ,  360  for a respective event recognizer, this list  326 ,  366  indicates the set of event recognizers, if any, that are to continue receiving sub-events even after the respective event recognizer has entered the exclusive state. For example, if the event recognizer for a single tap event enters the exclusive state, and the currently involved views include an event recognizer for a double tap event, then the list  320 ,  360  would list the double tap event recognizer so that a double tap event can be recognized even after a single tap event has been detected. Accordingly, the exclusivity exception list  326 ,  366  permits event recognizers to recognize different events that share common sequences of sub-events, e.g., a single tap event recognition does not preclude subsequent recognition of a double or triple tap event by other event recognizers.   Some event recognizer structures  320 ,  360 , may include a wait-for list  327 ,  367 . When included in the event recognizer structure  320 ,  360  for a respective event recognizer, this list  327 ,  367  indicates the set of event recognizers, if any, that must enter the event impossible or event canceled state before the respective event recognizer can recognize a respective event. In effect, the listed event recognizers have higher priority for recognizing an event than the event recognizer with the wait-for list  327 ,  367 .   A delay touch began flag  328 ,  368 , which, when set for an event recognizer, causes the event recognizer to delay sending sub-events (including a touch begin or finger down sub-event, and subsequent events) to the event recognizer&#39;s respective hit view or level until after it has been determined that the sequence of sub-events does not correspond to this event recognizer&#39;s event type. This flag can be used to prevent the hit view or level from ever seeing any of the sub-events in the case where the gesture is recognized. When the event recognizer fails to recognize an event, the touch began sub-event (and sub-sequent touch end sub-event) can be delivered to the hit view or level. In one example, delivering such sub-events to the hit view or level causes the user interface to briefly highlight an object, without invoking the action associated with that object.   A delay touch end flag  330 ,  370 , which, when set for an event recognizer, causes the event recognizer to delay sending a sub-event (e.g., a touch end sub-event) to the event recognizer&#39;s respective hit view or level until it has been determined that the sequence of sub-events does not correspond to this event recognizer&#39;s event type. This can be used to prevent the hit view or level from acting upon a touch end sub-event, in case the gesture is later recognized. As long as the touch end sub-event is not sent, a touch canceled can be sent to the hit view or level. If an event is recognized, the corresponding action by an application is preformed, and the touch end sub-event is delivered to the hit view or level.   A touch cancellation flag  332 ,  372 , which, when set for an event recognizer, causes the event recognizer to send touch or input cancellation to the event recognizer&#39;s respective hit view or hit level when it has been determined that the sequence of sub-events does not correspond to this event recognizer&#39;s event type. The touch or input cancellation sent to the hit view or level indicates that a prior sub-event (e.g., a touch began sub-event) has been cancelled. The touch or input cancellation may cause the input source handler&#39;s state (see  FIG.  4 B ) to enter the input sequence cancelled state  460  (discussed below).       

     In some embodiments, the exception list  326 ,  366  can also be used by non-exclusive event recognizers. In particular, when a non-exclusive event recognizer recognizes an event, subsequent sub-events are not delivered to the exclusive event recognizers associated with the currently active views, except for those exclusive event recognizers listed in the exception list  326 ,  366  of the event recognizer that recognized the event. 
     In some embodiments, event recognizers may be configured to utilize the touch cancellation flag in conjunction with the delay touch end flag to prevent unwanted sub-events from being delivered to the hit view. For example, the definition of a single tap gesture and the first half of a double tap gesture are identical. Once a single tap event recognizer successfully recognizes a single tap, an undesired action could take place. If the delay touch end flag is set, the single tap event recognizer is prevented from sending sub-events to the hit view until a single tap event is recognized. In addition, the wait-for list of the single tap event recognizer may identify the double-tap event recognizer, thereby preventing the single tap event recognizer from recognizing a single tap until the double-tap event recognizer has entered the event impossible state. The use of the wait-for list avoids the execution of actions associated with a single tap when a double tap gesture is performed. Instead, only actions associated with a double tap will be executed, in response to recognition of the double tap event. 
     Turning in particular to forms of user touches on touch-sensitive surfaces, as noted above, touches and user gestures may include an act that need not be instantaneous, e.g., a touch can include an act of moving or holding a finger against a display for a period of time. A touch data structure, however, defines the state of a touch (or, more generally, the state of any input source) at a particular time. Therefore, the values stored in a touch data structure may change over the course of a single touch, enabling the state of the single touch at different points in time to be conveyed to an application. 
     Each touch data structure can comprise various fields. In some embodiments, touch data structures may include data corresponding to at least the touch-specific fields  339  in  FIG.  3 B  or input source specific fields  379  in  FIG.  3 C . 
     For example, a “first touch for view” field  345  in  FIG.  3 B  ( 385  for “first touch for level” in  FIG.  3 C ) can indicate whether the touch data structure defines the first touch for the particular view (since the software element implementing the view was instantiated). A “time stamp” field  346 ,  386  can indicate the particular time to which the touch data structure relates. 
     Optionally, an “info” field  347 ,  387  can be used to indicate if a touch is a rudimentary gesture. For example, the “info” field  347 ,  387  can indicate whether the touch is a swipe and, if so, in which direction the swipe is oriented. A swipe is a quick drag of one or more fingers in a straight direction. API implementations (discussed below) can determine if a touch is a swipe and pass that information to the application through the “info” field  347 ,  387 , thus alleviating the application of some data processing that would have been necessary if the touch were a swipe. 
     Optionally, a “tap count” field  348  in  FIG.  3 B  (“event count” field  388  in  FIG.  3 C ) can indicate how many taps have been sequentially performed at the position of the initial touch. A tap can be defined as a quick pressing and lifting of a finger against a touch-sensitive panel at a particular position. Multiple sequential taps can occur if the finger is again pressed and released in quick succession at the same position of the panel. An event delivery system  122  can count taps and relay this information to an application through the “tap count” field  348 . Multiple taps at the same location are sometimes considered to be a useful and easy to remember command for touch enabled interfaces. Thus, by counting taps, the event delivery system  122  can again alleviate some data processing from the application. 
     A “phase” field  349 ,  389  can indicate a particular phase the touch-based gesture is currently in. The phase field  349 ,  389  can have various values, such as “touch phase began” which can indicate that the touch data structure defines a new touch that has not been referenced by previous touch data structures. A “touch phase moved” value can indicate that the touch being defined has moved from a prior position. A “touch phase stationary” value can indicate that the touch has stayed in the same position. A “touch phase ended” value can indicate that the touch has ended (e.g., the user has lifted his/her finger from the surface of a multi touch display). A “touch phase cancelled” value can indicate that the touch has been cancelled by the device. A cancelled touch can be a touch that is not necessarily ended by a user, but which the device has determined to ignore. For example, the device can determine that the touch is being generated inadvertently (i.e., as a result of placing a portable multi touch enabled device in one&#39;s pocket) and ignore the touch for that reason. Each value of the “phase field”  349 ,  389  can be an integer number. 
     Thus, each touch data structure can define what is happening with a respective touch (or other input source) at a particular time (e.g., whether the touch is stationary, being moved, etc.) as well as other information associated with the touch (such as position). Accordingly, each touch data structure can define the state of a particular touch at a particular moment in time. One or more touch data structures referencing the same time can be added in a touch event data structure that can define the states of all touches a particular view is receiving at a moment in time (as noted above, some touch data structures may also reference touches that have ended and are no longer being received). Multiple touch event data structures can be sent to the software implementing a view as time passes, in order to provide the software with continuous information describing the touches that are happening in the view. 
       FIG.  3 D  is a block diagram illustrating exemplary components for event handling (e.g., event handling components  390 ) in accordance with some embodiments. In some embodiments, memory  111  ( FIG.  1 A ) includes event recognizer global methods  312  and one or more applications (e.g.,  133 - 1  through  133 - 3 ). 
     In some embodiments, event recognizer global methods  312  include event monitor  311 , hit view determination module  314 , active event recognizer determination module  316 , and event dispatcher module  315 . In some embodiments, event recognizer global methods  312  are located within event delivery system  122  ( FIG.  1 A ). In some embodiments, event recognizer global methods  312  are implemented in operating system  118  ( FIG.  1 A ). Alternatively, event recognizer global methods  312  are implemented in a respective application  133 - 1 . In yet other embodiments, event recognizer global methods  312  are implemented as a stand-alone module, or a part of another module stored in memory  111  (e.g., a contact/motion module (not depicted)). 
     Event monitor  311  receives event information from one or more sensors  116 , touch-sensitive display  156 , and/or one or more input devices  128 . Event information includes information about an event (e.g., a user touch on touch-sensitive display  156 , as part of a multi-touch gesture or a motion of device  102 ) and/or a sub-event (e.g., a movement of a touch across touch-sensitive display  156 ). For example, event information for a touch event includes one or more of: a location and time stamp of a touch. Similarly, event information for a swipe event includes two or more of: a location, time stamp, direction, and speed of a swipe. Sensors  116 , touch-sensitive display  156 , and input devices  128  transmit information event and sub-event information to event monitor  311  either directly or through a peripherals interface, which retrieves and stores event information. Sensors  116  include one or more of: proximity sensor, accelerometer(s), gyroscopes, microphone, and video camera. In some embodiments, sensors  116  also include input devices  128  and/or touch-sensitive display  156 . 
     In some embodiments, event monitor  311  sends requests to sensors  116  and/or the peripherals interface at predetermined intervals. In response, sensors  116  and/or the peripherals interface transmit event information. In other embodiments, sensors  116  and the peripheral interface transmit event information only when there is a significant event (e.g., receiving an input beyond a predetermined noise threshold and/or for more than a predetermined duration). 
     Event monitor  311  receives event information and relays the event information to event dispatcher module  315 . In some embodiments, event monitor  311  determines one or more respective applications (e.g.,  133 - 1 ) to which to deliver the event information. In some embodiments, event monitor  311  also determines one or more respective application views  317  of the one or more respective applications to which to deliver the event information. 
     In some embodiments, event recognizer global methods  312  also include a hit view determination module  314  and/or an active event recognizer determination module  316 . 
     Hit view determination module  314 , if present, provides software procedures for determining where an event or a sub-event has taken place within one or more views, when touch-sensitive display  156  displays more than one view. Views are made up of controls and other elements that a user can see on the display. 
     Another aspect of the user interface associated with a respective application (e.g.,  133 - 1 ) is a set of views  317 , sometimes herein called application views or user interface windows, in which information is displayed and touch-based gestures occur. The application views (of a respective application) in which a touch is detected may correspond to a particular view within a view hierarchy of the application. For example, the lowest level view in which a touch is detected may be called the hit view, and the set of events that are recognized as proper inputs may be determined based, at least in part, on the hit view of the initial touch that begins a touch-based gesture. 
     Hit view determination module  314  receives information related to events and/or sub-events. When an application has multiple views organized in a hierarchy, hit view determination module  314  identifies a hit view as the lowest view in the hierarchy which should handle the event or sub-event. In most circumstances, the hit view is the lowest level view in which an initiating event or sub-event occurs (i.e., the first event or sub-event in the sequence of events and/or sub-events that form a gesture). Once the hit view is identified by the hit view determination module, the hit view typically receives all events and/or sub-events related to the same touch or input source for which it was identified as the hit view. However, the hit view is not always a sole view that receives all events and/or sub-events related to the same touch or input source for which it was identified as the hit view. Stated differently, in some embodiments, another application (e.g.,  133 - 2 ) or another view of the same application also receives at least a subset of the events and/or sub-events related to the same touch or input source regardless of whether a hit view has been determined for the touch or input source. 
     Active event recognizer determination module  316  determines which view or views within a view hierarchy should receive a particular sequence of events and/or sub-events. In some application contexts, active event recognizer determination module  316  determines that only the hit view should receive a particular sequence of events and/or sub-events. In other application contexts, active event recognizer determination module  316  determines that all views that include the physical location of an event or sub-event are actively involved views, and therefore determines that all actively involved views should receive a particular sequence of events and/or sub-events. In other application contexts, even if touch events and/or sub-events are entirely confined to the area associated with one particular view, views higher in the hierarchy still remain as actively involved views and thus the views higher in the hierarchy should receive a particular sequence of events and/or sub-events. Additionally, or alternatively, active event recognizer determination module  316  determines which application(s) in a programmatic hierarchy should receive a particular sequence of events and/or sub-events. Thus, in some embodiments, active event recognizer determination module  316  determines that only a respective application in the programmatic hierarchy should receive a particular sequence of events and/or sub-events. In some embodiments, active event recognizer determination module  316  determines that a plurality of applications in the programmatic hierarchy should receive a particular sequence of events and/or sub-events. 
     Event dispatcher module  315  dispatches the event information to an event recognizer (also called herein “gesture recognizer”) (e.g., event recognizer  325 - 1 ). In embodiments including active event recognizer determination module  316 , event dispatcher module  315  delivers the event information to an event recognizer determined by active event recognizer determination module  316 . In some embodiments, event dispatcher module  315  stores in an event queue the event information, which is retrieved by a respective event recognizer  325  (or event receiver  3031  in a respective event recognizer  325 ). 
     In some embodiments, a respective application (e.g.,  133 - 1 ) includes application internal state  321 , which indicates the current application view(s) displayed on touch-sensitive display  156  when the application is active or executing. In some embodiments, device/global internal state  134  ( FIG.  1 C ) is used by event recognizer global methods  312  to determine which application(s) is(are) currently active, and application internal state  321  is used by event recognizer global methods  312  to determine application views  317  to which to deliver event information. 
     In some embodiments, application internal state  321  includes additional information, such as one or more of: resume information to be used when application  133 - 1  resumes execution, user interface state information that indicates information being displayed or that is ready for display by application  133 - 1 , a state queue for enabling the user to go back to a prior state or view of application  133 - 1 , and a redo/undo queue of previous actions taken by the user. In some embodiments, application internal state  321  further includes contextual information/text and metadata  323 . 
     In some embodiments, application  133 - 1  includes one or more application views  317 , each of which has corresponding instructions for handling touch events that occur within a respective view of the application&#39;s user interface (e.g., a corresponding event handler  319 ). At least one application view  317  of the application  133 - 1  includes one or more event recognizers  325 . Typically, a respective application view  317  includes a plurality of event recognizers  325 . In other embodiments, one or more of event recognizers  325  are part of a separate module, such as a user interface kit (not shown) or a higher level object from which application  133 - 1  inherits methods and other properties. In some embodiments, a respective application view  317  also includes one or more of: data updater, object updater, GUI updater, and/or event data received. 
     A respective application (e.g.,  133 - 1 ) also includes one or more event handlers  319 . Typically, a respective application (e.g.,  133 - 1 ) includes a plurality of event handlers  319 . 
     A respective event recognizer  325 - 1  receives event information from event dispatcher module  315  (directly or indirectly through application  133 - 1 ), and identifies an event from the event information. Event recognizer  325 - 1  includes event receiver  3031  and event comparator  3033 . 
     The event information includes information about an event (e.g., a touch) or a sub-event (e.g., a touch movement). Depending on the event or sub-event, the event information also includes additional information, such as location of the event or sub-event. When the event or sub-event concerns motion of a touch, the event information may also include speed and direction of the sub-event. In some embodiments, events include rotation of the device from one orientation to another (e.g., from a portrait orientation to a landscape orientation, or vice versa), and the event information includes corresponding information about the current orientation (also called device attitude) of the device. 
     Event comparator  3033  compares the event information to one or more predefined gesture definitions (also called herein “event definitions”) and, based on the comparison, determines an event or sub-event, or determines or updates the state of an event or sub-event. In some embodiments, event comparator  3033  includes one or more gesture definitions  3035  (as described above, also called herein “event definitions”). Gesture definitions  3035  contain definitions of gestures (e.g., predefined sequences of events and/or sub-events), for example, gesture  1  ( 3037 - 1 ), gesture  2  ( 3037 - 2 ), and others. In some embodiments, sub-events in gesture definitions  3035  include, for example, touch begin, touch end, touch movement, touch cancellation, and multiple touching. In one example, the definition for gesture  1  ( 3037 - 1 ) is a double tap on a displayed object. The double tap, for example, comprises a first touch (touch begin) on the displayed object for a predetermined phase of the gesture, a first lift-off (touch end) for a next predetermined phase of the gesture, a second touch (touch begin) on the displayed object for a subsequent predetermined phase of the gesture, and a second lift-off (touch end) for a final predetermined phase of the gesture. In another example, the definition for gesture  2  ( 3037 - 2 ) includes a dragging on a displayed object. The dragging, for example, comprises a touch (or contact) on the displayed object, a movement of the touch across touch-sensitive display  156 , and lift-off of the touch (touch end). 
     In some embodiments, event recognizer  325 - 1  also includes information for event delivery  3039 . Information for event delivery  3039  includes references to corresponding event handlers  319 . Optionally, information for event delivery  3039  includes action-target pair(s). In some embodiments, in response to recognizing a gesture (or a part of a gesture), event information (e.g., action message(s)) is sent to one or more targets identified by the action-target pair(s). In other embodiments, in response to recognizing a gesture (or a part of a gesture), the action-target pair(s) are activated. 
     In some embodiments, gesture definitions  3035  include a definition of a gesture for a respective user-interface object. In some embodiments, event comparator  3033  performs a hit test to determine which user-interface object is associated with a sub-event. For example, in an application view in which three user-interface objects are displayed on touch-sensitive display  156 , when a touch is detected on touch-sensitive display  156 , event comparator  3033  performs a hit test to determine which of the three user-interface objects, if any, is associated with the touch (event). If each displayed object is associated with a respective event handler  319 , event comparator  3033  uses the result of the hit test to determine which event handler  319  should be activated. For example, event comparator  3033  selects an event handler  319  associated with the event and the object triggering the hit test. 
     In some embodiments, a respective gesture definition  3037  for a respective gesture also includes delayed actions that delay delivery of the event information until after it has been determined whether the sequence of events and/or sub-events does or does not correspond to the event recognizer&#39;s event type. 
     When a respective event recognizer  325 - 1  determines that the series of events and/or sub-events do not match any of the events in gesture definitions  3035 , the respective event recognizer  325 - 1  enters an event failed state, after which the respective event recognizer  325 - 1  disregards subsequent events and/or sub-events of the touch-based gesture. In this situation, other event recognizers, if any, that remain active for the hit view continue to track and process events and/or sub-events of an ongoing touch-based gesture. 
     In some embodiments, when no event recognizer for the hit view remains, the event information is sent to one or more event recognizers in a higher view in the view hierarchy. Alternatively, when no event recognizer for the hit view remains, the event information is disregarded. In some embodiments, when no event recognizer for views in the view hierarchy remains, the event information is sent to one or more event recognizers in a higher programmatic level in the programmatic hierarchy. Alternatively, when no event recognizer for views in the view hierarchy remains, the event information is disregarded. 
     In some embodiments, a respective event recognizer  325 - 1  includes event recognizer state  334 . Event recognizer state  334  includes a state of the respective event recognizer  325 - 1 . Examples of event recognizer states are described in more detail below with reference to  FIGS.  4 A- 4 B and  5 A- 5 C . 
     In some embodiments, event recognizer state  334  includes recognizer metadata and properties  3043 . In some embodiments, recognizer metadata and properties  3043  include one or more of the following: A) configurable properties, flags, and/or lists that indicate how the event delivery system should perform event and/or sub-event delivery to actively involved event recognizers; B) configurable properties, flags, and/or lists that indicate how event recognizers interact with one another; C) configurable properties, flags, and/or lists that indicate how event recognizers receive event information; D) configurable properties, flags, and/or lists that indicate how event recognizers may recognize a gesture; E) configurable properties, flags, and/or lists that indicate whether events and/or sub-events are delivered to varying levels in the view hierarchy; and F) references to corresponding event handlers  319 . 
     In some embodiments, event recognizer state  334  includes event/touch metadata  3045 . Event/touch metadata  3045  includes event/touch information about a respective event/touch that has been detected and corresponds to a respective gesture definition  3037  of gesture definitions  3035 . The event/touch information includes one or more of: a location, time stamp, speed, direction, distance, scale (or change in scale), and angle (or change in angle) of the respective event/touch. 
     In some embodiments, a respective event recognizer  325  activates event handler  319  associated with the respective event recognizer  325  when one or more particular events and/or sub-events of a gesture are recognized. In some embodiments, respective event recognizer  325  delivers event information associated with the event to event handler  319 . 
     Event handler  319 , when activated, performs one or more of: creating and/or updating data, creating and updating objects, and preparing display information and sending it for display on display  126  or touch-sensitive display  156 . 
     In some embodiments, a respective application view  317 - 2  includes view metadata  341 . As described above with respect to  FIG.  3 B , view metadata  341  includes data regarding a view. Optionally, view metadata  341  includes one or more of: stop property  342 , skip property  343 , NoHit skip property  344 , and other view metadata  329 . 
     In some embodiments, a first actively involved view within the view hierarchy may be configured to prevent delivery of a respective sub-event to event recognizers associated with that first actively involved view. This behavior can implement the skip property  343 . When the skip property is set for an application view, delivery of the respective sub-event is still performed for event recognizers associated with other actively involved views in the view hierarchy. 
     Alternately, a first actively involved view within the view hierarchy may be configured to prevent delivery of a respective sub-event to event recognizers associated with that first actively involved view unless the first actively involved view is the hit view. This behavior can implement the conditional NoHit skip property  344 . 
     In some embodiments, a second actively involved view within the view hierarchy is configured to prevent delivery of the respective sub-event to event recognizers associated with the second actively involved view and to event recognizers associated with ancestors of the second actively involved view. This behavior can implement the stop property  342 . 
       FIG.  3 E  is a block diagram illustrating exemplary classes and instances of gesture recognizers (e.g., event handling components  390 ) in accordance with some embodiments. 
     A software application (e.g., application  133 - 1 ) has one or more event recognizers  3040 . In some embodiments, a respective event recognizer (e.g.,  3040 - 2 ) is an event recognizer class. The respective event recognizer (e.g.,  3040 - 2 ) includes event recognizer specific code  338  (e.g., a set of instructions defining the operation of event recognizers) and state machine  340 . 
     In some embodiments, application state  321  of a software application (e.g., application  133 - 1 ) includes instances of event recognizers. Each instance of an event recognizer is an object having a state (e.g., event recognizer state  334 ). “Execution” of a respective event recognizer instance is implemented by executing corresponding event recognizer specific code (e.g.,  338 ) and updating or maintaining the state  334  of the event recognizer instance  3047 . The state  334  of event recognizer instance  3047  includes the state  3038  of the event recognizer instance&#39;s state machine  340 . 
     In some embodiments, application state  321  includes a plurality of event recognizer instances  3047 . A respective event recognizer instance  3047  typically corresponds to an event recognizer that has been bound (also called “attached”) to a view of the application. In some embodiments, one or more event recognizer instances  3047  are bound to a respective application in a programmatic hierarchy without reference to any particular view of the respective application. In some embodiments, application state  321  includes a plurality of instances (e.g.,  3047 - 1  to  3047 -L) of a respective event recognizer (e.g.,  3040 - 2 ). In some embodiments, application state  321  includes instances  3047  of a plurality of event recognizers (e.g.,  3040 - 1  to  3040 -R). 
     In some embodiments, a respective instance  3047 - 2  of a gesture recognizer  3040  includes event recognizer state  334 . As discussed above, in some embodiments, event recognizer state  334  includes recognizer metadata and properties  3043  and event/touch metadata  3045 . In some embodiments, event recognizer state  334  also includes view hierarchy reference(s)  336 , indicating to which view the respective instance  3047 - 2  of the gesture recognizer  3040 - 2  is attached. 
     In some embodiments, recognizer metadata and properties  3043  include the following, or a subset or superset thereof:
         exclusivity flag  324 ;   exclusivity exception list  326 ;   wait-for list  327 ;   delay touch began flag  328 ;   delay touch end flag  330 ; and   touch cancellation flag  332 .       

     In some embodiments, one or more event recognizers may be adapted to delay delivering one or more sub-events of the sequence of sub-events until after the event recognizer recognizes the event. This behavior reflects a delayed event. For example, consider a single tap gesture in a view for which multiple tap gestures are possible. In that case, a tap event becomes a “tap+delay” recognizer. In essence, when an event recognizer implements this behavior, the event recognizer will delay event recognition until it is certain that the sequence of sub-events does in fact correspond to its event definition. This behavior may be appropriate when a recipient view is incapable of appropriately responding to cancelled events. In some embodiments, an event recognizer will delay updating its event recognition status to its respective actively involved view until the event recognizer is certain that the sequence of sub-events does not correspond to its event definition. Delay touch began flag  328 , delay touch end flag  330 , and touch cancellation flag  332  are provided to tailor sub-event delivery techniques, as well as event recognizer and view status information updates to specific needs. 
     In some embodiments, recognizer metadata and properties  3043  include the following, or a subset or superset thereof:
         state machine state/phase  3038 , which indicates the state of a state machine (e.g.,  340 ) for the respective event recognizer instance (e.g.,  3047 - 2 ); state machine state/phase  3038  can have various state values, such as “event possible”, “event recognized”, “event failed”, and others, as described below; alternatively or additionally, state machine state/phase  3038  can have various phase values, such as “touch phase began” which can indicate that the touch data structure defines a new touch that has not been referenced by previous touch data structures; a “touch phase moved” value can indicate that the touch being defined has moved from a prior position; a “touch phase stationary” value can indicate that the touch has stayed in the same position; a “touch phase ended” value can indicate that the touch has ended (e.g., the user has lifted his/her finger from the surface of a multi touch display); a “touch phase cancelled” value can indicate that the touch has been cancelled by the device; a cancelled touch can be a touch that is not necessarily ended by a user, but which the device has determined to ignore; for example, the device can determine that the touch is being generated inadvertently (i.e., as a result of placing a portable multi touch enabled device in one&#39;s pocket) and ignore the touch for that reason; each value of state machine state/phase  3038  can be an integer number (called herein “gesture recognizer state value”);   action-target pair(s)  3051 , where each pair identifies a target to which the respective event recognizer instance sends the identified action message in response to recognizing an event or touch as a gesture or a part of a gesture;   delegate  3053 , which is a reference to a corresponding delegate when a delegate is assigned to the respective event recognizer instance; when a delegate is not assigned to the respective event recognizer instance, delegate  346  contains a null value; and   enabled property  3055 , indicating whether the respective event recognizer instance is enabled; in some embodiments, when the respective event recognizer instance is not enabled (e.g., disabled), the respective event recognizer instance does not process events or touches.       

     In some embodiments, exception list  326  can also be used by non-exclusive event recognizers. In particular, when a non-exclusive event recognizer recognizes an event or sub-event, subsequent events and/or sub-events are not delivered to the exclusive event recognizers associated with the currently active views, except for those exclusive event recognizers listed in exception list  326  of the event recognizer that recognized the event or sub-event. 
     In some embodiments, event recognizers may be configured to utilize the touch cancellation flag  332  in conjunction with the delay touch end flag  330  to prevent unwanted events and/or sub-events from being delivered to the hit view. For example, the definition of a single tap gesture and the first half of a double tap gesture are identical. Once a single tap event recognizer successfully recognizes a single tap, an undesired action could take place. If the delay touch end flag is set, the single tap event recognizer is prevented from sending sub-events to the hit view until a single tap event is recognized. In addition, the wait-for list of the single tap event recognizer may identify the double-tap event recognizer, thereby preventing the single tap event recognizer from recognizing a single tap until the double-tap event recognizer has entered the event impossible state. The use of the wait-for list avoids the execution of actions associated with a single tap when a double tap gesture is performed. Instead, only actions associated with a double tap will be executed, in response to recognition of the double tap event. 
     Turning in particular to forms of user touches on touch-sensitive surfaces, as noted above, touches and user gestures may include an act that need not be instantaneous, e.g., a touch can include an act of moving or holding a finger against a display for a period of time. A touch data structure, however, defines the state of a touch (or, more generally, the state of any input source) at a particular time. Therefore, the values stored in a touch data structure may change over the course of a single touch, enabling the state of the single touch at different points in time to be conveyed to an application. 
     Each touch data structure can comprise various entries. In some embodiments, touch data structures may include data corresponding to at least the touch-specific entries in event/touch metadata  3045  such as the following, or a subset or superset thereof:
         “first touch for view” entry  345 ;   “per touch info” entry  3051 , including “time stamp” information, which indicates the particular time to which the touch data structure relates (e.g., the time of touch); optionally, “per touch info” entry  3051  includes other information, such as a location of a corresponding touch; and   optional “tap count” entry  348 .       

     Thus, each touch data structure can define what is happening with a respective touch (or other input source) at a particular time (e.g., whether the touch is stationary, being moved, etc.) as well as other information associated with the touch (such as position). Accordingly, each touch data structure can define the state of a particular touch at a particular moment in time. One or more touch data structures referencing the same time can be added in a touch event data structure that can define the states of all touches a particular view is receiving at a moment in time (as noted above, some touch data structures may also reference touches that have ended and are no longer being received). Multiple touch event data structures can be sent to the software implementing a view as time passes, in order to provide the software with continuous information describing the touches that are happening in the view. 
     The ability to handle complex touch-based gestures, optionally including multi-touch gestures, can add complexity to the various software applications. In some cases, such additional complexity can be necessary to implement advanced and desirable interface features. For example, a game may require the ability to handle multiple simultaneous touches that occur in different views, as games often require the pressing of multiple buttons at the same time, or combining accelerometer data with touches on a touch-sensitive surface. However, some simpler applications and/or views need not require advanced interface features. For example, a simple soft button (i.e., a button that is displayed on a touch-sensitive display) may operate satisfactorily with single touches, rather than multi-touch functionality. In these cases, the underlying OS may send unnecessary or excessive touch data (e.g., multi-touch data) to a software component associated with a view that is intended to be operable by single touches only (e.g., a single touch or tap on a soft button). Because the software component may need to process this data, it may need to feature all the complexity of a software application that handles multiple touches, even though it is associated with a view for which only single touches are relevant. This can increase the cost of development of software for the device, because software components that have been traditionally easy to program in a mouse interface environment (i.e., various buttons, etc.) may be much more complex in a multi-touch environment. 
     In order to reduce the complexity in recognizing complex touch-based gestures, delegates can be used to control the behavior of event recognizers in accordance with some embodiments. As described below, delegates can determine, for example, whether a corresponding event recognizer (or gesture recognizer) can receive the event (e.g., touch) information; whether the corresponding event recognizer (or gesture recognizer) can transition from an initial state (e.g., event possible state) of state machine to another state; and/or whether the corresponding event recognizer (or gesture recognizer) can simultaneously recognize the event (e.g., touch) as a corresponding gesture without blocking other event recognizer(s) (or gesture recognizer(s)) from recognizing the event or getting blocked by other event recognizer(s) (or gesture recognizer(s)) recognizing the event. 
     It shall be understood, however, that the foregoing discussion regarding the complexity of evaluating and processing user touches on touch-sensitive surfaces also applies to all forms of user inputs to operate electronic device  102  with input devices  128 , not all of which are initiated on touch screens, e.g., coordinating mouse movement and mouse button presses with or without single or multiple keyboard presses or holds, device rotations or other movements, user movements such as taps, drags, scrolls, etc., on touch-pads, pen stylus inputs, oral instructions, detected eye movements, biometric inputs, detected physiological change in a user, and/or any combination thereof, which may be utilized as inputs corresponding to events and/or sub-events which define an event to be recognized. 
     Turning to the flow of event information,  FIG.  3 F  is a block diagram illustrating the flow of event information in accordance with some embodiments. Event dispatcher module  315  (e.g., in operating system  118  or application software  124 ) receives event information, and sends the event information to one or more applications (e.g.,  133 - 1  and  133 - 2 ). In some embodiments, application  133 - 1  includes a plurality of views (e.g.,  508 ,  510 , and  512  corresponding to views  317 ,  FIG.  3 D ) in view hierarchy  506  and a plurality of gesture recognizers ( 516 - 1  through  516 - 3 ) in the plurality of views. Application  133 - 1  also includes one or more gesture handlers  550 , which correspond to the target values in target-action pairs (e.g.,  552 - 1  and  552 - 2 ). In some embodiments, event dispatcher module  315  receives hit view information from hit view determination module  314  and sends event information to the hit view (e.g.,  512 ) or event recognizer(s) attached to the hit view (e.g.,  516 - 1  and  516 - 2 ). Additionally or alternatively, event dispatcher module  315  receives hit level information from hit level determination module  352  and sends event information to applications in the hit level (e.g.,  133 - 1  and  133 - 2 ) or one or more event recognizers (e.g.,  516 - 4 ) in the hit level applications. In some embodiments, one of the applications receiving the event information is a default application (e.g.,  133 - 2  may be a default application). In some embodiments, only a subset of gesture recognizers in each receiving application is allowed to (or configured to) receive the event information. For example, gesture recognizer  516 - 3  in application  133 - 1  does not receive the event information. The gesture recognizers that receive the event information are called herein receiving gesture recognizers. In  FIG.  3 F , receiving gesture recognizers  516 - 1 ,  516 - 2 , and  516 - 4  receive the event information, and compare the received event information with a respective gesture definition  3037  ( FIG.  3 D ) in the receiving gesture recognizers. In  FIG.  3 F , gesture recognizers  516 - 1  and  516 - 4  have respective gesture definitions that match the received event information, and send respective action messages (e.g.,  518 - 1  and  518 - 2 ) to corresponding gesture handlers (e.g.,  552 - 1  and  552 - 3 ). 
       FIG.  4 A  depicts an event recognizer state machine  400  containing four states. By managing state transitions in event recognizer state machine  400  based on received sub-events, an event recognizer effectively expresses an event definition. For example, a tap gesture may be effectively defined by a sequence of two, or optionally, three sub-events. First, a touch should be detected, and this will be sub-event  1 . For example, the touch sub-event may be a user&#39;s finger touching a touch-sensitive surface in a view that includes the event recognizer having state machine  400 . Second, an optional measured delay where the touch does not substantially move in any given direction (e.g., any movement of the touch position is less than a predefined threshold, which may be measured as a distance (e.g., 5 mm) or as a number of pixels (e.g., 5 pixels) on the display), and the delay is sufficiently short, would serve as sub-event  2 . Finally, termination of the touch (e.g., liftoff of the user&#39;s finger from the touch-sensitive surface) will serve as sub-event  3 . By coding the event recognizer state machine  400  to transition between states based upon receiving these sub-events, the event recognizer state machine  400  effectively expresses a tap gesture event definition. However, it should be noted that the states depicted in  FIG.  4 A  are exemplary states, and an event recognizer state machine  400  may contain more or fewer states and/or each state in the event recognizer state machine  400  may correspond to one of the depicted states or any other states. 
     In some embodiments, regardless of event type, the event recognizer state machine  400  begins in an event recognition begins state  405 , and may progress to any of the remaining states depending on what sub-event is received. To facilitate discussion of the event recognizer state machine  400 , the direct paths from the event recognition begins state  405  to the event recognized state  415 , the event possible state  410 , and event impossible state  420  will be discussed, followed by a description of the paths leading from the event possible state  410 . 
     Starting from event recognition begins state  405 , if a sub-event is received that, by itself comprises the event definition for an event, the event recognizer state machine  400  will transition to event recognized state  415 . 
     Starting from state event recognition begins  405 , if a sub-event is received that is not the first sub-event in an event definition, the event recognizer state machine  400  will transition to event impossible state  420 . 
     Starting from event recognition begins state  405 , if a sub-event is received that is the first and not final sub-event in a given event definition, the event recognizer state machine  400  will transition to event possible state  410 . If the next sub-event received is a second sub-event, but not the final sub-event in the given event definition, the event recognizer state machine  400  will remain in state event possible  410 . The event recognizer state machine  400  can remain in state event possible  410  for as long as the sequence of received sub-events continues to be part of the event definition. If, at any time the event recognizer state machine  400  is in event possible state  410 , and the event recognizer state machine  400  receives a sub-event that is not part of the event definition, it will transition to state event impossible  420 , thereby determining that the current event (if any) is not the type of event that corresponds to this event recognizer (i.e., the event recognizer corresponding to state  400 ). If, on the other hand, the event recognizer state machine  400  is in the event possible state  410 , and the event recognizer state machine  400  receives the last sub-event in an event definition, it will transition to the event recognized state  415 , thereby completing a successful event recognition. 
       FIG.  4 B  depicts an embodiment of an input source handling process  440 , having a finite state machine representing how views receive information about a respective input. It is noted that when there are multiple touches on the touch-sensitive surface of a device, each of the touches is a separate input source having its own finite state machine. In this embodiment, input source handling process  440  includes four states: input sequence begin  445 , input sequence continues  450 , input sequence ended  455 , and input sequence cancelled  460 . Input source handling process  440  may be used by a respective event recognizer, for example, when input is to be delivered to an application, but only after the completion of an input sequence is detected. Input source handling process  440  can be used with an application that is incapable of canceling or undoing changes made in response to an input sequence delivered to the application. It should be noted that the states depicted in  FIG.  4 B  are exemplary states, and input source handling process  440  may contain more or fewer states and/or each state in input source handling process  440  may correspond to one of the depicted states or any other states. 
     Starting from input sequence begin  445 , if an input is received that, by itself completes an input sequence, input source handling process  440  will transition to input sequence ended  455 . 
     Starting from input sequence begin  445 , if an input is received that indicates the input sequence terminated, input source handling process  440  will transition to input sequence cancelled  460 . 
     Starting from input sequence begin  445 , if an input is received that is the first and not final input in a input sequence, input source handling process  440  will transition to state input sequence continues  450 . If the next input received is the second input in an input sequence, the input handling process  440  will remain in state input sequence continues  450 . Input source handling process  440  can remain in state input sequence continues  450  for as long as the sequence of sub-events being delivered continue to be part of a given input sequence. If, at any time input source handling process  440  is in state input sequence continues  450 , and input source handling process  440  receives an input that is not part of the input sequence, it will transition to state input sequence cancelled  460 . If, on the other hand, input source handling process  440  is in input sequence continues  450 , and the input handling process  440  receives the last input in a given input definition, it will transition to the input sequence ended  455 , thereby successfully receiving a group of sub-events. 
     In some embodiments, input source handling process  440  may be implemented for particular views or programmatic levels. In that case, certain sequences of sub-events may result in transitioning to state input cancelled  460 . 
     As an example, consider  FIG.  4 C , which supposes an actively involved view, represented only by actively involved view input source handler  480  (hereafter “view  480 ”). View  480  includes a vertical swipe event recognizer, represented only by vertical swipe event recognizer  468  (hereafter “recognizer  468 ”) as one of its event recognizers. In this case, the recognizer  468  may require as part of its definition detecting: 1) a finger down  465 - 1 ; 2) an optional short delay  465 - 2 ; 3), vertical swiping of at least N pixels  465 - 3 ; and 4) a finger liftoff  465 - 4 . 
     For this example, the recognizer  468  also has its delay touch began flag  328  and touch cancellation flag  332  set. Now consider delivery of the following sequence of sub-events to recognizer  468 , as well as the view  480 :
         sub-event sequence  465 - 1 : detect finger down, which corresponds to recognizer  468 &#39;s event definition   sub-event sequence  465 - 2 : measure delay, which corresponds to recognizer  468 &#39;s event definition   sub-event sequence  465 - 3 : finger performs a vertical swiping movement compatible with vertical scrolling, but is less than N pixels, and therefore does not correspond to recognizer  468 &#39;s event definition   sub-event sequence  465 - 4 : detect finger liftoff, which corresponds to recognizer  468 &#39;s event definition       

     Here, recognizer  468  would successfully recognize sub-events  1  and  2  as part of its event definition, and accordingly, would be in state event possible  472  immediately prior to the delivery of sub-event  3 . Since recognizer  468  has its delay touch began flag  328  set, the initial touch sub-event is not sent to the hit view. Correspondingly, the view  480 &#39;s input source handling process  440  would still be in state input sequence begin immediately prior to the delivery of sub-event  3 . 
     Once delivery of sub-event  3  to recognizer  468  is complete, recognizer  468 &#39;s state transitions to event impossible  476 , and importantly, the recognizer  468  has now determined that the sequence of sub-events does not correspond to its specific vertical swipe gesture event type (i.e., it has decided the event is not a vertical swipe. In other words, recognition  474  as a vertical swipe does not occur in this example). The input source handling system  440  for view input source handler  480  will also update its state. In some embodiments, the state of the view input source handler  480  would proceed from the input sequence begins state  482  to the input sequence continues state  484  when the event recognizer sends status information indicating that it has begun recognizing an event. The view input source handler  480  proceeds to the input sequence cancelled state  488  when the touch or input ends without an event being recognized because the touch cancellation flag  322  of the event recognizer has been set. Alternately, if the touch cancellation flag  322  of the event recognizer had not been set, the view input source handler  480  proceeds to the input sequence ended state  486  when the touch of input ends. 
     Since event recognizer  468 &#39;s touch cancellation flag  332  is set, when the event recognizer  468  transitions to the event impossible state  476 , the recognizer will send a touch cancellation sub-event or message to the hit view corresponding to the event recognizer. As a result, the view input source handler  480  will transition to the state input sequence cancelled  488 . 
     In some embodiments, delivery of sub-event  465 - 4  is not germane to any event recognition decisions made by recognizer  468 , though view input source handler  480 &#39;s other event recognizers, if any, may continue to analyze the sequence of sub-events. 
     The following table presents in summarized tabular format the processing of this exemplary sub-event sequence  465  as related to the state of event recognizer  468  described above, along with the state of view input source handler  480 . In this example, the state of the view input source handler  480  proceeds from input sequence begin  445  to input sequence cancelled  488  because recognizer  468 &#39;s touch cancellation flag  332  was set: 
     
       
         
           
               
               
               
             
               
                   
               
               
                 Sub-Event Sequence 465 
                 State: Recognizer 468 
                 State: View 480 
               
               
                   
               
             
            
               
                 before delivery starts 
                 Event Recognition 
                   
               
               
                   
                 Begins 470 
               
               
                 detect finger down 
                 Event Possible 472 
                 Input Sequence 
               
               
                 465-1 
                   
                 Begins 482 
               
               
                 measure delay 465-2 
                 Event Possible 472 
                 Input Sequence 
               
               
                   
                   
                 Continues 484 
               
               
                 detect finger vertical 
                 Event Impossible 
                 Input Sequence 
               
               
                 swipe 465-3 
                 476 
                 Continues 484 
               
               
                 detect finger liftoff 
                 Event Impossible 
                 Input Sequence 
               
               
                 465-4 
                 476 
                 Cancelled 488 
               
               
                   
               
            
           
         
       
     
     Turning to  FIG.  5 A , attention is directed to an example of a sub-event sequence  520 , which is being received by a view that includes a plurality of event recognizers. For this example, two event recognizers are depicted in  FIG.  5 A , scrolling event recognizer  580  and tap event recognizer  590 . For purposes of illustration, the view search results panel  304  in  FIG.  3 A  will be related to the reception of the sub-event sequence  520 , and the state transitions in scrolling event recognizer  580  and tap event recognizer  590 . Note that in this example, the sequence of sub-events  520  defines a tap finger gesture on a touch-sensitive display or trackpad, but the same event recognition technique could be applied in a myriad of contexts, e.g., detecting a mouse button press, and/or in embodiments utilizing programmatic hierarchies of programmatic levels. 
     Before the first sub-event is delivered to view search results panel  304 , event recognizers  580  and  590  are in the event recognition begins states  582  and  592 , respectively. Following touch  301 , which is delivered as sub-event detect finger down  521 - 1  to actively involved event recognizers for view search results panel  304  as touch sub-event  301 - 2  (as well as to actively involved event recognizers for map view  305  as touch sub-event  301 - 3 ), scrolling event recognizer  580  transitions to state event possible  584 , and similarly, tap event recognizer  590  transitions to state event possible  594 . This is because the event definition of a tap and a scroll both begin with a touch such as detecting a finger down on a touch-sensitive surface. 
     Some definitions of tap and scroll gestures may optionally include a delay between an initial touch and any next step in the event definition. In all examples discussed here, the exemplar event definitions for both tap and scroll gestures recognize a delay sub-event following the first touch sub-event (detect finger down). 
     Accordingly, as sub-event measure delay  521 - 2  is delivered to event recognizers  580  and  590 , both remain in the event possible states  584  and  594 , respectively. 
     Finally, sub-event detect finger liftoff  521 - 3  is delivered to event recognizers  580  and  590 . In this case, the state transitions for event recognizers  580  and  590  are different, because the event definitions for tap and scroll are different. In the case of scrolling event recognizer  580 , the next sub-event to remain in state event possible would be to detect movement. Since the sub-event delivered is detect finger liftoff  521 - 3 , however, the scrolling event recognizer  580  transitions to state event impossible  588 . A tap event definition concludes with a finger liftoff sub-event though. Accordingly, tap event recognizer  590  transitions to state event recognized  596  after sub-event detect finger liftoff  521 - 3  is delivered. 
     Note that in some embodiments, as discussed above with respect to  FIGS.  4 B and  4 C , the input source handling process  440  discussed in  FIG.  4 B  may be used for various purposes at the view level. The following table presents in summarized tabular format the delivery of sub-event sequence  520  as related to event recognizers  580 ,  590 , and input source handling process  440 : 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Sub-Event 
                 State: Scrolling 
                 State: Tap 
                 State: Input 
               
               
                 Sequence 
                 Event Recognizer 
                 Event Recognizer 
                 Source Handling 
               
               
                 520 
                 580 
                 590 
                 Process 440 
               
               
                   
               
             
            
               
                 before delivery 
                 Event Recogni- 
                 Event Recogni- 
                   
               
               
                 starts 
                 tion Begins 582 
                 tion Begins 592 
               
               
                 Detect Finger 
                 Event 
                 Event 
                 Input Sequence 
               
               
                 Down 521-1 
                 Possible 584 
                 Possible 594 
                 Begin 445 
               
               
                 Measure 
                 Event 
                 Event 
                 Input Sequence 
               
               
                 Delay 521-2 
                 Possible 584 
                 Possible 594 
                 Continues 450 
               
               
                 Detect Finger 
                 Event impossible 
                 Event Recognized 
                 Input Sequence 
               
               
                 Liftoff 521-3 
                 588 
                 596 
                 Ended 455 
               
               
                   
               
            
           
         
       
     
     Turning to  FIG.  5 B , attention is directed to another example of a sub-event sequence  530 , which is being received by a view that includes a plurality of event recognizers. For this example, two event recognizers are depicted in  FIG.  5 B , scrolling event recognizer  580  and tap event recognizer  590 . For purposes of illustration, the view search results panel  304  in  FIG.  3 A  will be related to the reception of the sub-event sequence  530 , and the state transitions in scrolling event recognizer  580  and tap event recognizer  590 . Note that in this example, the sequence of sub-events  530  defines a scroll finger gesture on a touch-sensitive display, but the same event recognition technique could be applied in myriad contexts, e.g., detecting a mouse button press, mouse movement, and mouse button release, and/or in embodiments utilizing programmatic hierarchies of programmatic levels. 
     Before the first sub-event is delivered to actively involved event recognizers for view search results panel  304 , event recognizers  580  and  590  are in the event recognition begins states  582  and  592 , respectively. Following delivery of sub-events corresponding to touch  301  (as discussed above), scrolling event recognizer  580  transitions to state event possible  584 , and similarly, tap event recognizer  590  transitions to state event possible  594 . 
     As sub-event measure delay  531 - 2  is delivered to event recognizers  580  and  590 , both transition to the event possible states  584  and  594 , respectively. 
     Next, sub-event detect finger movement  531 - 3  is delivered to event recognizers  580  and  590 . In this case, the state transitions for event recognizers  580  and  590  are different because the event definitions for tap and scroll are different. In the case of scrolling event recognizer  580 , the next sub-event to remain in state event possible is to detect movement, so the scrolling event recognizer  580  remains in the event possible state  584  when it receives sub-event detect finger movement  531 - 3 . As discussed above, however, the definition for a tap concludes with a finger liftoff sub-event, so tap event recognizer  590  transitions to the state event impossible  598 . 
     Finally, sub-event detect finger liftoff  531 - 4  is delivered to event recognizers  580  and  590 . Tap event recognizer is already in the event impossible state  598 , and no state transition occurs. Scrolling event recognizer  580 &#39;s event definition concludes with detecting a finger liftoff. Since the sub-event delivered is detect finger liftoff  531 - 4 , the scrolling event recognizer  580  transitions to state event recognized  586 . It is noted that a finger movement on a touch sensitive surface may generate multiple movement sub-events, and therefore a scroll may be recognized before liftoff and continue until liftoff. 
     The following table presents in summarized tabular format the delivery of sub-event sequence  530  as related to event recognizers  580 ,  590 , and input source handling process  440 : 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Sub-Event 
                 State: Scrolling 
                 State: Tap 
                 State: Input 
               
               
                 Sequence 
                 Event Recognizer 
                 Event Recognizer 
                 Source Handling 
               
               
                 530 
                 580 
                 590 
                 Process 440 
               
               
                   
               
             
            
               
                 before delivery 
                 Event Recogni- 
                 Event Recogni- 
                   
               
               
                 starts 
                 tion Begins 582 
                 tion Begins 592 
               
               
                 detect finger 
                 Event 
                 Event 
                 Input Sequence 
               
               
                 down 531-1 
                 Possible 584 
                 Possible 594 
                 Begins 445 
               
               
                 measure 
                 Event 
                 Event 
                 Input sequence 
               
               
                 delay 531-2 
                 Possible 584 
                 Possible 594 
                 continues 450 
               
               
                 detect finger 
                 Event 
                 Event Impossible 
                 Input sequence 
               
               
                 movement 
                 Possible 584 
                 598 
                 continues 450 
               
               
                 531-3 
               
               
                 detect finger 
                 Event Recognized 
                 Event Impossible 
                 Input sequence 
               
               
                 liftoff 531-4 
                 586 
                 598 
                 ended 455 
               
               
                   
               
            
           
         
       
     
     Turning to  FIG.  5 C , attention is directed to another example of a sub-event sequence  540 , which is being received by a view that includes a plurality of event recognizers. For this example, two event recognizers are depicted in  FIG.  5 C , double tap event recognizer  570  and tap event recognizer  590 . For purposes of illustration, the map view  305  in  FIG.  3 A  will be related to the reception of the sub-event sequence  540 , and the state transitions in double tap event recognizer  570  and tap event recognizer  590 . Note that in this example, the sequence of sub-events  540  defines a double tap gesture on a touch-sensitive display, but the same event recognition technique could be applied in myriad contexts, e.g., detecting a mouse double click, and/or in embodiments utilizing programmatic hierarchies of programmatic levels. 
     Before the first sub-event is delivered to actively involved event recognizers for map view  305 , event recognizers  570  and  590  are in the event recognition begins states  572  and  592 , respectively. Following delivery of sub-events related to touch sub-event  301  to map view  304  (as described above), double tap event recognizer  570  and tap event recognizer  590  transition to states event possible  574  and  594 , respectively. This is because the event definition of a tap and a double tap both begin with a touch such as detecting a finger down  541 - 1  on a touch-sensitive surface. 
     As sub-event measure delay  541 - 2  is delivered to event recognizers  570  and  590 , both remain in states event possible  574  and  594 , respectively. 
     Next, sub-event detect finger liftoff  541 - 3  is delivered to event recognizers  570  and  590 . In this case, the state transitions for event recognizers  580  and  590  are different because the exemplar event definitions for tap and double tap are different. In the case of tap event recognizer  590 , the final sub-event in the event definition is to detect finger liftoff, so the tap event recognizer  590  transitions to the event recognized state  596 . 
     Double tap recognizer  570  remains in state event possible  574 , however, since a delay has begun, regardless of what the user may ultimately do. The complete event recognition definition for a double tap requires another delay, followed by a complete tap sub-event sequence though. This creates an ambiguous situation as between the tap event recognizer  590 , which is already in state event recognized  576 , and the double tap recognizer  570 , which is still in state event possible  574 . 
     Accordingly, in some embodiments, event recognizers may implement exclusivity flags and exclusivity exception lists as discussed above with respect to  FIGS.  3 B and  3 C . Here, the exclusivity flag  324  for tap event recognizer  590  would be set, and additionally, exclusivity exception list  326  for tap event recognizer  590  would be configured to continue permitting delivery of sub-events to some event recognizers (such as double tap event recognizer  570 ) after tap event recognizer  590  enters the state event recognized  596 . 
     While tap event recognizer  590  remains in state event recognized  596 , sub-event sequence  540  continues to be delivered to double tap event recognizer  570 , where sub-events measure delay  541 - 4 , detect finger down  541 - 5 , and measure delay  541 - 6 , keep the double tap event recognizer  570  in the state event possible  574 ; delivery of the final sub-event of sequence  540 , detect finger liftoff  541 - 7  transitions double tap event recognizer  570  to state event recognized  576 . 
     At this point, the map view  305  takes the event double tap as recognized by event recognizer  570 , rather than the single tap event recognized by tap event recognizer  590 . The decision to take the double tap event is made in light of the combination of the tap event recognizer  590 &#39;s exclusivity flag  324  being set, the tap event recognizer  590 &#39;s exclusivity exception list  326  including a double tap event, and the fact that both the tap event recognizer  590  and the double tap event recognizer  570  both successfully recognized their respective event types. 
     The following table presents in summarized tabular format the delivery of sub-event sequence  540  as related to event recognizers  570  and  590 , and sub-event handling process  440 : 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                 Sub-Event 
                 State: Double Tap 
                 State: Tap 
                 State: Input 
               
               
                 Sequence 
                 Event Recognizer 
                 Event Recognizer 
                 Source Handling 
               
               
                 540 
                 570 
                 590 
                 Process 440 
               
               
                   
               
             
            
               
                 before delivery 
                 Event Recogni- 
                 Event Recogni- 
                   
               
               
                 starts 
                 tion Begins 572 
                 tion Begins 592 
               
               
                 detect finger 
                 Event 
                 Event 
                 Input Sequence 
               
               
                 down 541-1 
                 Possible 574 
                 Possible 594 
                 Begins 445 
               
               
                 measure 
                 Event 
                 Event 
                 Input sequence 
               
               
                 delay 541-2 
                 Possible 574 
                 Possible 594 
                 continues 450 
               
               
                 detect finger 
                 Event 
                 Event Recognized 
                 Input sequence 
               
               
                 liftoff 541-3 
                 Possible 574 
                 596 
                 continues 450 
               
               
                 measure 
                 Event 
                 Event Recognized 
                 Input sequence 
               
               
                 delay 541-4 
                 Possible 574 
                 596 
                 continues 450 
               
               
                 detect finger 
                 Event 
                 Event Recognized 
                 Input sequence 
               
               
                 down 541-5 
                 Possible 574 
                 596 
                 continues 450 
               
               
                 measure 
                 Event 
                 Event Recognized 
                 Input sequence 
               
               
                 delay 541-6 
                 Possible 574 
                 596 
                 continues 450 
               
               
                 detect finger 
                 Event Recognized 
                 Event Recognized 
                 Input sequence 
               
               
                 liftoff 541-7 
                 576 
                 596 
                 ended 455 
               
               
                   
               
            
           
         
       
     
     In another embodiment, in the event scenario of  FIG.  5 C , the single tap gesture is not recognized, because the single tap event recognizer has a wait-for list that identifies the double tap event recognizer. As a result, a single tap gesture is not recognized until (if ever) the double tap event recognizer enters the event impossible state. In this example, in which a double tap gesture is recognized, the single tap event recognizer would remain in the event possible state until the double tap gesture is recognized, at which point the single tap event recognizer would transition to the event impossible state. 
     Attention is now directed to  FIGS.  6 A and  6 B , which are flow diagrams illustrating an event recognition method in accordance with some embodiments. The method  600  is performed at an electronic device, which in some embodiments, may be an electronic device  102 , as discussed above. In some embodiments, the electronic device may include a touch sensitive surface configured to detect multi-touch gestures. Alternatively, the electronic device may include a touch screen configured to detect multi-touch gestures. 
     The method  600  is configured to execute software that includes a view hierarchy with a plurality of views. The method  600  displays  608  one or more views of the view hierarchy, and executes  610  one or more software elements. Each software element is associated with a particular view, and each particular view includes one or more event recognizers, such as those described in  FIGS.  3 B and  3 C  as event recognizer structures  320  and  360 , respectively. 
     Each event recognizer generally includes an event definition based on one or more sub-events, where the event definition may be implemented as a state machine, see e.g.,  FIG.  3 B  state machine  340 . Event recognizers also generally include an event handler, which specifies an action for a target, and is configured to send the action to the target in response to the event recognizer detecting an event corresponding to the event definition. 
     In some embodiments, at least one of the plurality of event recognizers is a gesture recognizer having a gesture definition and a gesture handler as noted in step  612  of  FIG.  6 A . 
     In some embodiments, the event definition defines a user gesture as noted in step  614  of  FIG.  6 A . 
     Alternatively, event recognizers have a set of event recognition states  616 . These event recognition states may include at least an event possible state, an event impossible state, and an event recognized state. 
     In some embodiments, the event handler initiates preparation  618  of its corresponding action for delivery to the target if the event recognizer enters the event possible state. As discussed above with respect to  FIG.  4 A  and the examples in  FIGS.  5 A- 5 C , the state machines implemented for each event recognizer generally include an initial state, e.g., state event recognition begins  405 . Receiving a sub-event that forms the initial part of an event definition triggers a state change to the event possible state  410 . Accordingly, in some embodiments, as an event recognizer transitions from the state event recognition begins  405  to the state event possible  410 , the event recognizer&#39;s event handler may begin preparing its particular action to deliver to the event recognizer&#39;s target after an event is successfully recognized. 
     On the other hand, in some embodiments, the event handler may terminate preparation  620  of its corresponding action if the event recognizer enters the state event impossible  420 . In some embodiments, terminating the corresponding action includes canceling any preparation of the event handler&#39;s corresponding action. 
     The example of  FIG.  5 B  is informative for this embodiment since tap event recognizer  590  may have initiated preparation  618  of its action, but then, once the sub-event detect finger movement  531 - 3  is delivered to the tap event recognizer  590 , the recognizer  590  will transition to the event impossible state  598 ,  578 . At that point, tap event recognizer  590  may terminate preparation  620  of the action for which it had initiated preparation  618 . 
     In some embodiments, the event handler completes preparation  622  of its corresponding action for delivery to the target if the event recognizer enters the event recognized state. The example of  FIG.  5 C  illustrates this embodiment since a double tap is recognized by actively involved event recognizers for the map view  305 , which in some implementations, would be the event bound to selecting and/or executing the search result depicted by map view  305 . Here, after the double tap event recognizer  570  successfully recognizes the double tap event comprised of the sub-event sequence  540 , map view  305 &#39;s event handler completes preparation  622  of its action, namely, indicating that it has received an activation command. 
     In some embodiments, the event handler delivers  624  its corresponding action to the target associated with the event recognizer. Continuing with the example of  FIG.  5 C , the action prepared, i.e. the activation command of the map view  305 , would be delivered to the specific target associated with the map view  305 , which may be any suitable programmatic method or object. 
     Alternatively, the plurality of event recognizers may independently process  626  the sequence of one or more sub-events in parallel. 
     In some embodiments, one or more event recognizers may be configured as exclusive event recognizers  628 , as discussed above with respect to  FIGS.  3 B and  3 C &#39;s exclusivity flags  324  and  364 , respectively. When an event recognizer is configured as an exclusive event recognizer, the event delivery system prevents any other event recognizers for actively involved views (except those listed in the exception list  326 ,  366  of the event recognizer that recognizes the event) in the view hierarchy from receiving subsequent sub-events (of the same sequence of sub-events) after the exclusive event recognizer recognizes an event. Furthermore, when a non-exclusive event recognizer recognizes an event, the event delivery system prevents any exclusive event recognizers for actively involved views in the view hierarchy from receiving subsequent sub-events, except for those (if any) listed in the exception list  326 ,  366  of the event recognizer that recognizes the event. 
     In some embodiments, exclusive event recognizers may include  630  an event exception list, as discussed above with respect to  FIGS.  3 B and  3 C &#39;s exclusivity exception lists  326  and  366 , respectively. As noted in the discussion of  FIG.  5 C  above, an event recognizer&#39;s exclusivity exception list can be used to permit event recognizers to continue with event recognition even when the sequence of sub-events making up their respective event definitions overlap. Accordingly, in some embodiments, the event exception list includes events whose corresponding event definitions have repetitive sub-events  632 , such as the single tap/double tap event example of  FIG.  5 C . 
     Alternately, the event definition may define a user input operation  634 . 
     In some embodiments, one or more event recognizers may be adapted to delay delivering every sub-event of the sequence of sub-events until after the event is recognized. 
     The method  600  detects  636  a sequence of one or more sub-events, and in some embodiments, the sequence of one or more sub-events may include primitive touch events  638 . Primitive touch events may include, without limitation, basic components of a touch-based gesture on a touch-sensitive surface, such as data related to an initial finger or stylus touch down, data related to initiation of multi-finger or stylus movement across a touch-sensitive surface, dual finger movements in opposing directions, stylus lift off from a touch-sensitive surface, etc. 
     Sub-events in the sequence of one or more sub-events can include many forms, including without limitation, key presses, key press holds, key press releases, button presses, button press holds, button press releases, joystick movements, mouse movements, mouse button presses, mouse button releases, pen stylus touches, pen stylus movements, pen stylus releases, oral instructions, detected eye movements, biometric inputs, and detected physiological changes in a user, among others. 
     The method  600  identifies  640  one of the views of the view hierarchy as a hit view. The hit view establishes which views in the view hierarchy are actively involved views. An example is depicted in  FIG.  3 A , where the actively involved views  303  include search results panel  304 , and maps view  305  because touch sub-event  301  contacted the area associated with the maps view  305 . 
     In some embodiments, a first actively involved view within the view hierarchy may be configured  642  to prevent delivery of the respective sub-event to event recognizers associated with that first actively involved view. This behavior can implement the skip property discussed above with respect to  FIGS.  3 B and  3 C  ( 330  and  370 , respectively). When the skip property is set for an event recognizer, delivery of the respective sub-event is still performed for event recognizers associated with other actively involved views in the view hierarchy. 
     Alternately, a first actively involved view within the view hierarchy may be configured  644  to prevent delivery of the respective sub-event to event recognizers associated with that first actively involved view unless the first actively involved view is the hit view. This behavior can implement the conditional skip property discussed above with respect to  FIGS.  3 B and  3 C  ( 332  and  372 , respectively). 
     In some embodiments, a second actively involved view within the view hierarchy is configured  646  to prevent delivery of the respective sub-event to event recognizers associated with the second actively involved view and to event recognizers associated with ancestors of the second actively involved view. This behavior can implement the stop property discussed above with respect to  FIGS.  3 B and  3 C  ( 328  and  368 , respectively). 
     The method  600  delivers  648  a respective sub-event to event recognizers for each actively involved view within the view hierarchy. In some embodiments, event recognizers for actively involved views in the view hierarchy process the respective sub-event prior to processing a next sub-event in the sequence of sub-events. Alternately, event recognizers for the actively involved views in the view hierarchy make their sub-event recognition decisions while processing the respective sub-event. 
     In some embodiments, event recognizers for actively involved views in the view hierarchy may process the sequence of one or more sub-events concurrently  650 ; alternatively, event recognizers for actively involved views in the view hierarchy may process the sequence of one or more sub-events in parallel. 
     In some embodiments, one or more event recognizers may be adapted to delay delivering  652  one or more sub-events of the sequence of sub-events until after the event recognizer recognizes the event. This behavior reflects a delayed event. For example, consider a single tap gesture in a view for which multiple tap gestures are possible. In that case, a tap event becomes a “tap+delay” recognizer. In essence, when an event recognizer implements this behavior, the event recognizer will delay event recognition until it is certain that the sequence of sub-events does in fact correspond to its event definition. This behavior may be appropriate when a recipient view is incapable of appropriately responding to cancelled events. In some embodiments, an event recognizer will delay updating its event recognition status to its respective actively involved view until the event recognizer is certain that the sequence of sub-events does not correspond to its event definition. As discussed above with respect to  FIGS.  3 B and  3 C , delay touch began flag  328 ,  368 , delay touch end flag  330 ,  370 , and touch cancellation flag  332 ,  372  are provided to tailor sub-event delivery techniques, as well as event recognizer and view status information updates to specific needs. 
       FIGS.  7 A- 7 S  illustrate exemplary user interfaces and user inputs recognized by event recognizers for navigating through concurrently open applications in accordance with some embodiments. The user interfaces in these figures are used to illustrate the processes described below, including the processes in  FIGS.  8 A- 8 B ,  FIGS.  9 A- 9 C , and  FIGS.  10 A- 10 B . 
     Although many of the examples which follow will be given with reference to inputs on touch screen display  156  (where the touch sensitive surface and the display are combined), in some embodiments, the device detects inputs on a touch-sensitive surface that is separate from the display (e.g., a touchpad or trackpad). In some embodiments the touch-sensitive surface has a primary axis that corresponds to a primary axis on the display. In accordance with these embodiments, the device detects contacts with the touch-sensitive surface at locations that correspond to respective locations on the display. In this way, user inputs detected by the device on the touch-sensitive surface are used by the device to manipulate the user interface on the display of the electronic device when the touch-sensitive surface is separate from the display. It should be understood that similar methods may be used for other user interfaces described herein. 
       FIG.  7 A  illustrates an exemplary user interface (“home screen”  708 ) on electronic device  102  in accordance with some embodiments. Similar user interfaces may be implemented on electronic devices  102 . In some embodiments, home screen  708  is displayed by an application launcher software application, sometimes called a springboard. In some embodiments, the user interface on touch screen  156  includes the following elements, or a subset or superset thereof:
         Signal strength indicator(s)  702  for wireless communication(s), such as cellular and Wi-Fi signals;   Time  704 ; and   Battery status indicator  706 .       

     The exemplary user interface includes a plurality of application icons  5002  (e.g.,  5002 - 25  through  5002 - 38 ). From the home screen  708 , a finger gesture can be used to launch an application. For example, tap finger gesture  701  at a location that corresponds to application icon  5002 - 36  initiates launching an email application. 
     In  FIG.  7 B , in response to detecting the finger gesture  701  on application icon  5002 - 36 , the email application is launched and email application view  712 - 1  is displayed on touch screen  156 . A user may launch other applications in a similar manner. For example, a user may press home button  710  from any application view  712  to return to home screen  708  ( FIG.  7 A ), and launch other applications with finger gestures on respective application icons  5002  on home screen  708 . 
       FIGS.  7 C- 7 G  illustrate that respective applications are sequentially launched in response to detecting respective finger gestures at locations corresponding to respective application icons  5002  on home screen  708 , and that respective user interfaces (i.e., respective application views) are displayed in turn. In particular,  FIG.  7 C  illustrates that media store application view  712 - 2  is displayed in response to a finger gesture on application icon  5002 - 32 . In  FIG.  7 D , notes application view  712 - 3  is displayed in response to a finger gesture on application icon  5002 - 30 .  FIG.  7 E  illustrates that map application view  712 - 4  is displayed in response to a finger gesture on application icon  5002 - 27 . In  FIG.  7 F , weather application view  712 - 5  is displayed in response to a finger gesture on application icon  5002 - 28 .  FIG.  7 G  illustrates that web browser application view  712 - 6  is displayed in response to a finger gesture on application icon  5002 - 37 . In some embodiments, a sequence of open applications corresponds to the launching of an email application, a media store application, a notes application, a map application, a weather application, and a web browser application. 
       FIG.  7 G  also illustrates a finger gesture  703  (e.g., a tap gesture) on a user interface object (e.g., a bookmark icon). In some embodiments, in response to detecting the finger gesture  703  on the bookmark icon, the web browser application displays a list of bookmarks on touch screen  156 . Similarly, a user may interact with a displayed application (e.g., the web browser application) with other gestures (e.g., a tap gesture on the address user interface object, which allows the user to type in a new address or modify the displayed address, typically with an on-screen keyboard; a tap gesture on any of links in the displayed web page, which initiates navigating to a web page corresponding to the selected link; etc.). 
     In  FIG.  7 G , a first predefined input (e.g., a double-click  705  on home button  710 ) is detected. Alternatively, a multi-finger swipe gesture (e.g., a three-finger swipe-up gesture as illustrated with movements of finger contacts  707 ,  709 , and  711 ) is detected on touch screen  156 . 
       FIG.  7 H  illustrates that, in response to detecting the first predefined input (e.g., double-click  705  or the multi-finger swipe gesture including finger contacts  707 ,  709 , and  711 ), a portion of web browser application view  712 - 6  and application icon area  716  are concurrently displayed. In some embodiments, in response to detecting the first predefined input, the device enters into an application view selection mode for selecting one of the concurrently open applications, and the portion of web browser application view  712 - 6  and application icon area  716  are concurrently displayed as part of the application view selection mode. Application icon area  716  includes a group of open application icons that correspond to at least some of the plurality of concurrently open applications. In this example, the portable electronic device has multiple applications that are concurrently open (e.g., the email application, the media store application, the notes application, the map application, the weather application, and the web browser application), although they are not all simultaneously displayed. As illustrated in  FIG.  7 H , application icon area  506  includes application icons (e.g.,  5004 - 2 ,  5004 - 4 ,  5004 - 6 , and  5004 - 8 ) for the weather application, the map application, the notes application, and the media store application (i.e., four applications that immediately follow the currently displayed application, the web browser application, in the sequence of open applications). In some embodiments, the sequence or order of open application icons displayed in application icon area  716  corresponds to the sequence of open applications in the predetermined sequence (e.g., weather, map, notes, and media store applications). 
       FIG.  7 H  also illustrates that gesture  713  (e.g., a tap gesture) is detected on open application icon  5004 - 8 . In some embodiments, in response to detecting gesture  713 , a corresponding application view (e.g., media store application view  712 - 2 ,  FIG.  7 C ) is displayed. 
       FIG.  7 H  illustrates that a left-swipe gesture  715  is detected at a location corresponding to application icon area  716 . In  FIG.  7 I , in response to detecting left-swipe gesture  715 , the application icons (e.g.,  5004 - 2 ,  5004 - 4 ,  5004 - 6 , and  5004 - 8 ) in application icon area  716  are scrolled. As a result of scrolling, application icon  5004 - 12  for the email application is displayed in application icon area  506  instead of previously displayed application icons (e.g.,  5004 - 2 ,  5004 - 4 ,  5004 - 6 , and  5004 - 8 ). 
     In  FIG.  7 J , a gesture of a first type (e.g., a multi-finger left-swipe gesture including movements of finger contacts  717 ,  719 , and  721 ) is detected on web browser application view  712 - 6 .  FIG.  7 K  illustrates that, in response to detecting the gesture of the first type, weather application view  712 - 5  is displayed on touch screen  156 . It should be noted that the weather application is next to the web browser application in the sequence of open applications. 
       FIG.  7 K  also illustrates that a second gesture of the first type (e.g., a multi-finger left-swipe gesture including movements of finger contacts  723 ,  725 , and  727 ) is detected on weather application view  712 - 5 .  FIG.  7 L  illustrates that, in response to detecting the second gesture of the first type, map application view  712 - 4  is displayed on touch screen  156 . It should be noted that the map application is next to the weather application in the sequence of open applications. 
       FIG.  7 L  also illustrates that a third gesture of the first type (e.g., a multi-finger left-swipe gesture including movements of finger contacts  729 ,  731 , and  733 ) is detected on map application view  712 - 4 .  FIG.  7 M  illustrates that, in response to detecting the third gesture of the first type, notes application view  712 - 3  is displayed on touch screen  156 . It should be noted that the notes application is next to the map application in the sequence of open applications. 
       FIG.  7 M  also illustrates that a fourth gesture of the first type (e.g., a multi-finger left-swipe gesture including movements of finger contacts  735 ,  737 , and  739 ) is detected on notes application view  712 - 3 .  FIG.  7 N  illustrates that, in response to detecting the fourth gesture of the first type, media store application view  712 - 2  is displayed on touch screen  156 . It should be noted that the media store application is next to the notes application in the sequence of open applications. 
       FIG.  7 N  also illustrates that a fifth gesture of the first type (e.g., a multi-finger left-swipe gesture including movements of finger contacts  741 ,  743 , and  745 ) is detected on media store application view  712 - 2 .  FIG.  7 O  illustrates that, in response to detecting the fifth gesture of the first type, email application view  712 - 1  is displayed on touch screen  156 . It should be noted that the email application is next to the media store application in the sequence of open applications. 
       FIG.  7 O  also illustrates that a sixth gesture of the first type (e.g., a multi-finger left-swipe gesture including movements of finger contacts  747 ,  749 , and  751 ) is detected on email application view  712 - 1 .  FIG.  7 P  illustrates that, in response to detecting the sixth gesture of the first type, web browser application view  712 - 6  is displayed on touch screen  156 . It should be noted that the web browser application is on one end of the sequence of open applications, and the email application is on the opposite end of the sequence of open applications. 
       FIG.  7 P  also illustrates that a gesture of a second type (e.g., a multi-finger right-swipe gesture including movements of finger contacts  753 ,  755 , and  757 ) is detected on web browser application view  712 - 6 .  FIG.  7 Q  illustrates that, in some embodiments, in response to detecting the gesture of the second type, email application view  712 - 1  is displayed on touch screen  156 . 
     Referring to  FIG.  7 R , a multi-finger gesture (e.g., a five-finger pinch gesture including movements of finger contacts  759 ,  761 ,  763 ,  765 , and  767 ) is detected on web browser application view  712 - 6 .  FIG.  7 S  illustrates that, while detecting the multi-finger gesture on touch screen  156 , web browser application view  712 - 6  and at least a portion of home screen  708  are concurrently displayed. As illustrated, web browser application view  712 - 6  is displayed at a reduced scale. The reduced scale is adjusted in accordance with the multi-finger gesture while the multi-finger gesture is detected on the touch screen  156 . For example, the reduced scale decreases with further pinching of finger contacts  759 ,  761 ,  763 ,  765 , and  767  (i.e., web browser application view  712 - 6  is displayed at a smaller scale). Alternatively, the reduced scale increases with depinching of finger contacts  759 ,  761 ,  763 ,  765 , and  767  (i.e., web browser application view  712 - 6  is displayed at a larger scale than before). 
     In some embodiments, when the multi-finger gesture ceases to be detected, web browser application view  712 - 6  ceases to be displayed, and the entire home screen  708  is displayed. Alternatively, when the multi-finger gesture ceases to be detected, it is determined whether the entire home screen  708  is to be displayed or web browser application view  712 - 6  is to be displayed at a full-screen scale. In some embodiments, the determination is made based on the reduced scale when the multi-finger gesture ceases to be displayed (e.g., if the application view is displayed at a scale smaller than a predefined threshold when the multi-finger gesture ceases to be detected, the entire home screen  708  is displayed; if the application view is displayed at a scale larger than the predefined threshold when the multi-finger gesture ceases to be detected, the application view is displayed at a full-screen scale without a display of home screen  708 ). In some embodiments, the determination is made also based on the speed of the multi-finger gesture. 
       FIGS.  8 A and  8 B  are flow diagrams illustrating event recognition method  800  in accordance with some embodiments. Method  800  is performed ( 802 ) at an electronic device with a touch-sensitive display (e.g., device  102 ,  FIG.  1 B ). The electronic device is configured to execute at least a first software application and a second software application. The first software application includes a first set of one or more gesture recognizers, and the second software application includes one or more views and a second set of one or more gesture recognizers (e.g., application  133 - 2  has gesture recognizer  516 - 4 , and application  133 - 1  has gesture recognizers  516 - 1  through  516 - 3  and views  508 ,  510 , and  512 ,  FIG.  3 F ). Respective gesture recognizers have corresponding gesture handlers (e.g., gesture handler  552 - 1  corresponds to gesture recognizer  516 - 1  and gesture handler  552 - 3  corresponds to gesture recognizer  516 - 4 ). The first set of one or more gesture recognizers is typically different from the second set of one or more gesture recognizers. 
     Method  800  allows a user to control with a gesture a hidden open application that is not currently displayed on a display of the electronic device (e.g., the first software application), such as a background application, a suspended application, or a hibernated application. Thus, the user can perform operations that are not provided by the application currently displayed on the display of the electronic device (e.g., the second software application) but are provided by one of the currently open applications (e.g., displaying a home screen or switching to a next software application using gestures for a hidden application launcher software application). 
     In some embodiments, the first software application is ( 804 ) an application launcher (e.g., a springboard). For example, as shown in  FIG.  7 A , the application launcher displays a plurality of application icons  5002  that correspond to a plurality of applications. The application launcher receives a user-selection of an application icon  5002  (e.g., based on a finger gesture on touch screen  156 ), and in response to receiving the user-selection, launches an application corresponding to the selected application icon  5002 . 
     The second software application is typically a software application launched by the application launcher. As illustrated in  FIGS.  7 A and  7 B , the application launcher receives information about tap gesture  701  on email application icon  5002 - 36 , and launches an email application. In response, the email application displays email application view  712 - 1  on touch screen  156 . The second application may be any application that corresponds to application icons  5002  ( FIG.  7 A ) or any other application that can be launched by the application launcher (e.g., media store application,  FIG.  7 C ; notes application,  FIG.  7 D ; map application,  FIG.  7 E ; weather application,  7 F; web browser application,  FIG.  7 G ; etc.). In the following description of method  800 , an application launcher is used as an exemplary first software application and a web browser application is used as an exemplary second software application. 
     In some embodiments, the electronic device has only two software applications in the programmatic hierarchy: an application launcher and one other software application (typically a software application corresponding to one or more views displayed on touch screen  156  of electronic device  102 ). 
     In some embodiments, the first software application is ( 806 ) an operating system application. As used herein, an operating system application refers to an application that is integrated with an operating system  118  ( FIGS.  1 A- 1 C ). An operating system application typically resides in core OS level  208  or operating system API software  206  in  FIG.  2   . An operating system application is typically not removable by a user, whereas other applications typically may be installed or removed by the user. In some embodiments, the operating system application includes the application launcher. In some embodiments, the operating system application includes a settings application (e.g., an application for displaying/modifying system settings or one or more values in device/global internal state  134 ,  FIG.  1 C ). In some embodiments, the operating system application includes accessibility module  127 . In some embodiments, the electronic device has only three software applications in the programmatic hierarchy: an application launcher, a settings application, and one other application (typically a software application corresponding to one or more views displayed on touch screen  156  of electronic device  102 ). 
     The electronic device displays ( 808 ) at least a subset of the one or more views of the second software application (e.g., web browser application view  712 - 6 ,  FIG.  7 G ). 
     In some embodiments, the displaying includes ( 810 ) displaying at least a subset of the one or more views of the second software application without displaying any view of the first software application. For example, in  FIG.  7 G , no view of the application launcher (e.g., home screen  708 ) is displayed. 
     In some embodiments, the displaying includes ( 812 ) displaying at least a subset of the one or more views of the second software application without displaying a view of any other application. For example, in  FIG.  7 G , only one or more views of the web browser application are displayed. 
     While displaying at least the subset of the one or more views of the second software application, the electronic device detects ( 814 ) a sequence of touch inputs on the touch-sensitive display (e.g., gesture  703 , which includes a touch-down event and a touch-up event; or another gesture, which includes touch-down of finger contacts  707 ,  709 , and  711 , movements of finger contacts  707 ,  709 , and  711  across touch screen  156 , and lift-off of finger contacts  707 ,  709 , and  711 ). The sequence of touch inputs includes a first portion of one or more touch inputs and a second portion of one or more touch inputs subsequent to the first portion. As used herein, the term “sequence” refers to the order in which one or more touch events happens. For example, in the sequence of touch inputs including finger contacts  707 ,  709 , and  711 , the first portion may include the touch-down of finger contacts  707 ,  709 , and  711 , and the second portion may include the movements of finger contacts  707 ,  709 , and  711 , and lift-off of finger contacts  707 ,  709 , and  711 . 
     In some embodiments, the detecting occurs ( 816 ) while touch inputs in the first portion of one or more touch inputs at least partially overlap at least one of the displayed views of the second software application. In some embodiments, even though the touch inputs at least partially overlap at least one of the displayed views of the second software application, the first software application receives the first portion of one or more touch inputs. For example, the application launcher receives the first portion of touch inputs on the displayed views of the web browser ( FIG.  7 G ), even though the application launcher is not displayed. 
     During a first phase of detecting the sequence of touch inputs ( 818 ), the electronic device delivers ( 820 ) the first portion of one or more touch inputs to the first software application and the second software application (e.g., using event dispatcher module  315 ,  FIG.  3 D ), identifies ( 822 ) from gesture recognizers in the first set, one or more matching gesture recognizers that recognize the first portion of one or more touch inputs (e.g., using event comparator  3033  in each gesture recognizer (typically, each receiving gesture recognizer) in the first set,  FIG.  3 D ), and processes ( 824 ) the first portion of one or more touch inputs with one or more gesture handlers corresponding to the one or more matching gesture recognizers (e.g., activating corresponding event handler(s)  319 ,  FIG.  3 D ). 
     In some embodiments, the first phase of detecting the sequence of touch inputs is a phase of detecting the first portion of one or more touch inputs. 
     Regarding the delivering operation ( 820 ), in some embodiments, the first software application, after receiving the first portion of one or more inputs, delivers the first portion of one or more touch inputs to at least a subset of gesture recognizers in the first set, and the second software application, after receiving the first portion of one or more inputs, delivers the first portion of one or more touch inputs to at least a subset of gesture recognizers in the second set. In some embodiments, the electronic device or an event dispatcher module (e.g.,  315 ,  FIG.  3 D ) in the electronic device delivers the first portion of one or more touch inputs to at least a subset of gesture recognizers in the first set and the second set (e.g., event dispatcher module  315  delivers the first portion of one or more touch inputs to gesture recognizers  516 - 1 ,  516 - 2 , and  516 - 4 ,  FIG.  3 F ). 
     For example, when the finger gesture including finger contacts  707 ,  709 , and  711  is detected on touch screen  156  ( FIG.  7 G ), the touch-down event is delivered to one or more gesture recognizers of the application launcher and one or more gesture recognizers of the web browser application. In another example, a touch-down event of tap gesture  703  ( FIG.  7 G ) is delivered to one or more gesture recognizers of the application launcher and one or more gesture recognizers of the web browser application. 
     In some embodiments, when no gesture recognizer in the first set recognizes the first portion of one or more touch inputs (e.g., a mismatch between detected events and the gesture definition or the gesture is not completed), processing the first portion of one or more touch inputs includes performing a null operation (e.g., the device does not update the displayed user interface). 
     In some embodiments, the electronic device identifies from gesture recognizers in the second set, one or more matching gesture recognizers that recognizer the first portion of one or more touch inputs. The electronic device processes the first portion of one or more touch inputs with one or more gesture handlers corresponding to the one or more matching gesture recognizers. For example, in response to tap gesture  703  ( FIG.  7 G ) delivered to one or more gesture recognizers of the web browser application, a matching gesture recognizer in the web browser application (e.g., a gesture recognizer that recognizes a tap gesture on the bookmark icon,  FIG.  7 G ) processes tap gesture  703  by displaying a list of bookmarks on touch screen  156 . 
     In some embodiments, during a second phase of detecting the sequence of touch inputs, subsequent to the first phase, the electronic device delivers ( 826 ,  FIG.  8 B ) the second portion of one or more touch inputs to the first software application without delivering the second portion of one or more touch inputs to the second software application (e.g., using event dispatcher module  315 ,  FIG.  3 D ), identifies from the one or more matching gesture recognizers a second matching gesture recognizer that recognizes the sequence of touch inputs (e.g., using event comparator  3033  in each matching gesture recognizer,  FIG.  3 D ), and processes the sequence of touch inputs with a gesture handler corresponding to the respective matching gesture recognizer. In some embodiments, the second phase of detecting the sequence of touch inputs is a phase of detecting the second portion of one or more touch inputs. 
     For example, when the finger gesture including finger contacts  707 ,  709 , and  711  is detected on touch screen  156  ( FIG.  7 G ), the touch movement and lift-off events are delivered to one or more gesture recognizers of the application launcher without delivering the touch events to the web browser application. The electronic device identifies a matching gesture recognizer (e.g., a three-finger swipe-up gesture recognizer) of the application launcher, and processes the sequence of touch inputs with a gesture handler corresponding to the three-finger swipe-up gesture recognizer. 
     The second software application does not receive the second portion of one or more touch inputs during the second phase, typically because the first software application has a priority over the second software application (e.g., in the programmatic hierarchy). Thus, in some embodiments, when a gesture recognizer in the first software application recognizes the first portion of one or more touch inputs, the one or more gesture recognizers in the first software application exclusively receive the second subsequent portion of one or more touch inputs. In addition, the second software application may not receive the second portion of one or more touch inputs during the second phase, because no gesture recognizer in the second software application matches the first portion of one or more touch inputs. 
     In some embodiments, processing the sequence of touch inputs with the gesture handler corresponding to the respective matching gesture recognizer includes ( 834 ) displaying in a first predefined area of the touch-sensitive display a group of open application icons that correspond to at least some of a plurality of concurrently open applications, and concurrently displaying at least a subset of the one or more views of the second software application. For example, in  FIG.  7 H , application icons  5004  in predefined area  716  corresponds to concurrently open applications of the electronic device. In some embodiments, application icons  5004  in predefined area  716  are displayed in accordance with a sequence of open applications. In  FIG.  7 H , the electronic device concurrently displays predefined area  716  and a subset of web browser application view  712 - 6 . 
     In some embodiments, processing the sequence of touch inputs with the gesture handler corresponding to the respective matching gesture recognizer includes ( 828 ) displaying one or more views of the first software application. For example, in response to a multi-finger pinch gesture ( FIG.  7 R ), the electronic device displays home screen  708  ( FIG.  7 A ). In some embodiments, displaying the one or more views of the first software application includes displaying the one or more views of the first software application without concurrently displaying a view corresponding to any other software application (e.g.,  FIG.  7 A ). 
     In some embodiments, processing the sequence of touch inputs with the gesture handler corresponding to the respective matching gesture recognizer includes ( 830 ) replacing the display of the one or more views of the second software application with display of one or more views of the first software application (e.g., displaying home screen  708 ,  FIG.  7 A ). Thus, the one or more views of the second software application ceases to be displayed after the one or more views of the first software application are displayed. In some embodiments, replacing the display of the one or more views of the second software application with display of one or more views of the first software application includes displaying the one or more views of the first software application without concurrently displaying a view corresponding to any other software application ( FIG.  7 A ). 
     In some embodiments, the electronic device concurrently executes ( 832 ) the first software application, the second software application, and a third software application. In some embodiments, processing the sequence of touch inputs with the gesture handler corresponding to the respective matching gesture recognizer includes replacing the one or more displayed views of the second software application with one or more views of the third software application. For example, in response to a multi-finger swipe gesture, the electronic device replaces the display of web browser application view  712 - 6  with a display of weather application view  712 - 5  ( FIGS.  7 J- 7 K ). In some embodiments, replacing the one or more displayed views of the second software application with one or more views of the third software application includes displaying the one or more views of the third software application without concurrently displaying a view corresponding to any other software application. In some embodiments, the third software application is next to the second software application in the sequence of open applications. 
     In some embodiments, processing the sequence of touch inputs with the gesture handler corresponding to the respective matching gesture recognizer includes launching a settings application. For example, in response to a ten-finger tap gesture, the electronic device launches the settings application. 
     Note that details of the processes described above with respect to method  800  are also applicable in an analogous manner to method  900  described below. For brevity, these details are not repeated below. 
       FIGS.  9 A- 9 C  are flow diagrams illustrating event recognition method  900  in accordance with some embodiments. Method  900  is performed ( 902 ) at an electronic device with a touch-sensitive display. The electronic device is configured to execute at least a first software application and a second software application. The first software application includes a first set of one or more gesture recognizers, and the second software application includes one or more views and a second set of one or more gesture recognizers. Respective gesture recognizers have corresponding gesture handlers. In some embodiments, the first set of one or more gesture recognizers is different from the second set of one or more gesture recognizers. 
     Method  900  allows a user to control with a gesture a hidden open application that is not currently displayed on a display of the electronic device (e.g., the first software application), such as a background application, a suspended application, or a hibernated application Thus, the user can perform operations that are not provided by the application currently displayed on the display of the electronic device (e.g., the second software application) but are provided by one of the currently open applications (e.g., displaying a home screen or switching to a next software application using gestures for a hidden application launcher software application). 
     In some embodiments, the first software application is ( 904 ) an application launcher (e.g., a springboard). In some embodiments, the first software application is ( 906 ) an operating system application. In the following description of method  900 , an application launcher is used as an exemplary first software application and a web browser application is used as an exemplary second software application. 
     The electronic device displays ( 908 ) a first set of one or more views (e.g., web browser application view  712 - 6 ,  FIG.  7 G ). The first set of one or more views includes at least a subset of the one or more views of the second software application. For example, the second software application may have a plurality of application views (e.g., application views  317  of application  133 - 1 ,  FIG.  3 D ), and the electronic device displays at least one view of the plurality of application views. In some embodiments, the subset includes the entire one or more views of the second software application. 
     In some embodiments, displaying the first set of one or more views includes ( 910 ) displaying the first set of one or more views without displaying any view of the first software application (e.g., web browser application view  712 - 6 ,  FIG.  7 G ). 
     In some embodiments, displaying the first set of one or more views includes ( 912 ) displaying the first set of one or more views without displaying a view of any other software application. For example, in  FIG.  7 G , only one or more views of the web browser application are displayed. 
     While displaying the first set of the one or more views, the electronic device detects ( 914 ) a sequence of touch inputs on the touch-sensitive display, and determines ( 920 ) whether at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs. For example, while displaying web browser application view  712 - 6  ( FIG.  7 G ), the device determines whether gesture recognizers for the application launcher recognizes the first portion of the touch inputs. The sequence of touch inputs includes a first portion of one or more touch inputs and a second portion of one or more touch inputs subsequent to the first portion (i.e., the second portion is after the first portion). 
     In some embodiments, the sequence of touch inputs at least partially overlaps ( 916 ) at least one of the one or more displayed views of the second software application. For example, the application launcher receives the first portion of touch inputs on web browser application view  712 - 6  ( FIG.  7 G ), even though the application launcher is not displayed. 
     In some embodiments, prior to a determination that at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs, the electronic device concurrently delivers ( 918 ) the first portion of one or more touch inputs to the first software application and the second software application. For example, both the application launcher and the web browser application receive the touch-down event of finger contacts  707 ,  709 , and  711  ( FIG.  7 G ) prior to a determination that at least one gesture recognizer in the application launcher recognizes the touch-down event. 
     In accordance with a determination that at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs ( 922 ,  FIG.  9 B ), the electronic device delivers ( 924 ) the sequence of touch inputs to the first software application without delivering the sequence of touch inputs to the second software application, determines ( 926 ) whether at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the sequence of touch inputs, and in accordance with a determination that at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the sequence of touch inputs, processes ( 928 ) the sequence of touch inputs with the at least one gesture recognizer in the first set of one or more gesture recognizers that recognizes the sequence of touch inputs. 
     For example, when the touch-down and touch-movement of three finger contacts  707 ,  709 , and  711  are detected on touch screen  156  ( FIG.  7 G ), the electronic device identifies that at least a three-finger swipe-up gesture recognizer of the application launcher recognizes the touch inputs. Thereafter, the electronic device delivers subsequent touch events (e.g., lift-off of finger contact  707 ,  709 , and  711 ) to the application launcher without delivering the subsequent touch events to the web browser application. The electronic device further identifies that the three-finger swipe-up gesture recognizer recognizes the sequence of touch inputs, and processes the sequence of touch inputs with a gesture handler corresponding to the three-finger swipe-up gesture recognizer. 
     In some embodiments, processing the sequence of touch inputs with the at least one gesture recognizer in the first set of one or more gesture recognizers includes ( 930 ) displaying one or more views of the first software application. For example, in response to detecting a multi-finger pinch gesture ( FIG.  7 R ), the electronic device displays home screen  708  ( FIG.  7 A ). 
     In some embodiments, processing the sequence of touch inputs with the at least one gesture recognizer in the first set of one or more gesture recognizers includes ( 932 ) replacing the display of the first set of one or more views with display of one or more views of the first software application (e.g., displaying home screen  708 ,  FIG.  7 A , which is part of the application launcher software application). 
     In some embodiments, the electronic device concurrently executes the first software application, the second software application, and a third software application; and processing the sequence of touch inputs with the at least one gesture recognizer in the first set of one or more gesture recognizers includes ( 934 ) replacing the first set of one or more views with one or more views of the third software application. In some embodiments, replacing the first set of one or more views with one or more views of the third software application includes displaying the one or more views of the third software application without concurrently displaying a view corresponding to any other software application. For example, in response to a multi-finger swipe gesture, the electronic device replaces the display of web browser application view  712 - 6  with a display of weather application view  712 - 5  ( FIGS.  7 J- 7 K ). 
     In some embodiments, processing the sequence of touch inputs with the at least one gesture recognizer in the first set of one or more gesture recognizers includes ( 936 ) displaying in a first predefined area of the touch-sensitive display a group of open application icons that correspond to at least some of a plurality of concurrently open applications, and concurrently displaying at least a subset of the first set of one or more views. For example, in  FIG.  7 H , application icons  5004  in predefined area  716  corresponds to concurrently open applications of the electronic device. In some embodiments, application icons  5004  in predefined area  716  are displayed in accordance with a sequence of open applications. In  FIG.  7 H , the electronic device concurrently displays predefined area  716  and a subset of web browser application view  712 - 6 . 
     In accordance with a determination that no gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs ( 938 ,  FIG.  9 C ), the electronic device delivers ( 940 ) the sequence of touch inputs to the second software application, determines ( 942 ) whether at least one gesture recognizer in the second set of one or more gesture recognizers recognizes the sequence of touch inputs, and in accordance with a determination that at least one gesture recognizer in the second set of one or more gesture recognizers recognizes the sequence of touch inputs, processes ( 944 ) the sequence of touch inputs with the at least one gesture recognizer in the second set of one or more gesture recognizers that recognizes the sequence of touch inputs. 
     For example, when the first portion of one or more touch inputs is tap gesture (e.g.,  703 ,  FIG.  7 G ), and no gesture recognizer in the application launcher recognizes the tap gesture, the electronic device delivers the tap gesture to the web browser application, and determines whether at least one gesture recognizer of the web browser application recognizes the tap gesture. When the web browser application (or a gesture recognizer of the web browser application) recognizes tap gesture  703  on the bookmark icon, the electronic device processes tap gesture  703  with a corresponding gesture handler. 
       FIGS.  10 A- 10 B  are flow diagrams illustrating an event recognition method in accordance with some embodiments. Note that details of the processes described above with respect to methods  600 ,  800 , and  900  are also applicable in an analogous manner to method  1000  described below. For brevity, these details are not repeated below. 
     Method  1000  is performed ( 1002 ) at an electronic device with an internal state (e.g., device/global internal state  134 ,  FIG.  1 C ). The electronic device is configured to execute software that includes a view hierarchy with a plurality of views. 
     In method  1000 , at least one gesture recognizer has a plurality of gesture definitions. This helps the gesture recognizer work in different distinct operating modes. For example, a device may have a normal operating mode and an accessibility operating mode. In the normal operating mode, a next application gesture is used to move between applications, and the next application gesture is defined as a three-finger left-swipe gesture. In the accessibility operating mode, the three-finger left-swipe gesture is used to perform a different function. Thus, a gesture different from the three-finger left-swipe is needed in the accessibility operating mode to correspond to the next application gesture (e.g., a four-finger left-swipe gesture in the accessibility operating mode). By having multiple gesture definitions associated with the next application gesture, the device can select one of the gesture definitions for the next application gesture, depending on the current operating mode. This provides flexibility in using the gesture recognizer in different operating modes. In some embodiments, a plurality of gesture recognizers with multiple gesture definitions is adjusted depending on the operating mode (e.g., gestures performed with three fingers in the normal operating mode are performed with four fingers in the accessibility operating mode). 
     In some embodiments, the internal state includes ( 1016 ) one or more settings for an accessibility operating mode (e.g., the internal state indicates whether the device is operating in the accessibility operating mode). 
     In some embodiments, the software is ( 1018 ) or includes an application launcher (e.g., a springboard). 
     In some embodiments, the software is ( 1020 ) or includes an operating system application (e.g., an application integrated with an operating system of the device). 
     The electronic device displays ( 1004 ) one or more views of the view hierarchy. 
     The electronic device executes ( 1006 ) one or more software elements. Each software element is associated with a particular view (e.g., application  133 - 1  has one or more application views  317 ,  FIG.  3 D ), and each particular view includes one or more event recognizers (e.g., event recognizers  325 ,  FIG.  3 D ). Each event recognizer has one or more event definitions based on one or more sub-events, and an event handler (e.g., gesture definitions  3035  and a reference to a corresponding event handler in event delivery information  3039 ,  FIG.  3 D ). The event handler specifies an action for a target, and is configured to send the action to the target in response to the event recognizer detecting an event corresponding to a particular event definition of the one or more event definitions (e.g., an event definition selected from the one or more event definitions when the event recognizer has multiple event definitions, or a sole event definition when the event recognizer has only one event definition). 
     The electronic device detects ( 1008 ) a sequence of one or more sub-events. 
     The electronic device identifies ( 1010 ) one of the views of the view hierarchy as a hit view. The hit view establishes which views in the view hierarchy are actively involved views. 
     The electronic device delivers ( 1012 ) a respective sub-event to event recognizers for each actively involved view within the view hierarchy. In some embodiments, the one or more actively involved views in the view hierarchy include the hit view. In some embodiments, the one or more actively involved views in the view hierarchy include a default view (e.g., home screen  708  of the application launcher). 
     At least one event recognizer for actively involved views in the view hierarchy has ( 1014 ) a plurality of event definitions, one of which is selected in accordance with the internal state of the electronic device. For example, event recognizer  325 - 1  has a plurality of gesture definitions (e.g.,  3037 - 1  and  3037 - 2 ,  FIG.  3 D ). In some embodiments, event recognizer  325 - 1  selects one of the plurality of gesture definitions in event recognizer  325 - 1  based on one or more values in device/global internal state  134  ( FIG.  1 C ). The at least one event recognizer then processes the respective sub-event prior to processing a next sub-event in the sequence of sub-events in accordance with the selected event definition. In some embodiments, each of two or more event recognizers for actively involved views in the view hierarchy has a plurality of event definitions, one of which is selected in accordance with the internal state of the electronic device. In such embodiments, at least one of the two or more event recognizers processes the respective sub-event prior to processing the next sub-event in the sequence of sub-events in accordance with the selected event definition. 
     For example,  FIGS.  7 J- 7 K  illustrate a next-application gesture that initiates displaying an application view of a next application. In some embodiments, the application launcher includes a next-application gesture recognizer, which includes a gesture definition that matches a three-finger left-swipe gesture. For purposes of this example, assume that the next-application gesture recognizer also includes a gesture definition that corresponds to a four-finger left-swipe gesture. When one or more values in device/global internal state  134  are set to default value(s), the next-application gesture recognizer uses the three-finger left-swipe gesture definition and does not use the four-finger left-swipe gesture definition. When the one or more values in device/global internal state  134  are modified (e.g., by using accessibility module  127 ,  FIG.  1 C ), the next-application gesture recognizer uses the four-finger left-swipe gesture definition and does not use the three-finger left-swipe gesture definition. Thus, in this example, when the one or more values in device/global internal state  134  are modified, a four-finger left-swipe gesture initiates displaying an application view of a next application. 
     Similarly,  FIGS.  7 R- 7 S  illustrate that a home screen gesture initiates displaying web browser application view  712 - 6  at a reduced scale and displaying at least a portion of home screen  708  in response to detecting a five-finger pinch gesture. Based on device/global internal state  134  and gesture definitions in a home screen gesture recognizer, a four-finger pinch gesture, a three-finger pinch gesture, or any other suitable gesture may be used to initiate displaying web-browser application view  712 - 6  at a reduced scale and displaying at least a portion of home screen  708 . 
     In some embodiments, the plurality of event definitions includes ( 1020 ) a first event definition corresponding to a first swipe gesture with a first number of fingers and a second event definition corresponding to a second swipe gesture with a second number of fingers distinct from the first number of fingers. For example, the plurality of event definitions for a respective gesture recognizer may include a three-finger swipe gesture and a four-finger swipe gesture. 
     In some embodiments, the plurality of event definitions includes a first event definition corresponding a first gesture of a first kind with a first number of fingers and a second event definition corresponding to a second gesture of the first kind with a second number of fingers distinct from the first number of fingers (e.g., a one-finger tap gesture and a two-finger tap gesture, a two-finger pinch gesture and a three-finger pinch gesture, etc.). 
     In some embodiments, the plurality of event definitions includes a first event definition corresponding to a first gesture and a second event definition corresponding to a second gesture distinct from the first gesture (e.g., a swipe gesture and a pinch gesture, a swipe gesture and a tap gesture, etc.). 
     In some embodiments, a respective definition of the plurality of event definitions is selected ( 1022 ) for a respective event recognizer in accordance with the internal state of the electronic device and a determination (by the electronic device) that the respective event definition does not correspond to an event definition of any event recognizer for the actively involved views other than the respective event recognizer. 
     For example, a respective gesture recognizer may have two event definitions: a first event definition corresponding to a three-finger left swipe gesture that is typically used for a normal operating mode and a second event definition corresponding to a four-finger left swipe gesture that is typically used for an accessibility operating mode. When the internal state of the electronic device is set in a way such that the electronic device operates in the accessibility mode, the electronic device determines whether the four-finger left swipe gesture for the second event definition is used by any other event recognizer for the actively involved views. If the four-finger left swipe gesture is not used by any other event recognizer for the actively involved views, the four-finger left swipe gesture is selected for the respective gesture recognizer in the accessibility operating mode. On the other hand, if the four-finger left swipe gesture is used by any other event recognizer for the actively involved views, the three-finger left swipe gesture is used for the respective gesture recognizer even in the accessibility operating mode. This prevents two or more gesture recognizers from undesirably responding to a same gesture. 
     In some embodiments, a respective definition of the plurality of event definitions is selected for a respective event recognizer in accordance with the internal state of the electronic device and a determination (by the electronic device) that the respective event definition does not correspond to an event definition of any event recognizer (including event recognizers for the actively involved views and any other views) other than the respective event recognizer. 
     In some embodiments, two or more event recognizers for actively involved views in the view hierarchy each have ( 1024 ) a respective plurality of event definitions, and a respective event definition of the respective plurality of event definitions is selected for a respective event recognizer in accordance with the internal state of the electronic device and a determination (by the electronic device) that the respective event definition does not correspond to any event definition selected for any event recognizer with two or more event definitions other than the respective event recognizer. 
     For example, actively involved views may have a first gesture recognizer and a second gesture recognizer. In this example, the first gesture recognizer has: a first event definition corresponding to a three-finger left swipe gesture that is typically used for a normal operating mode and a second event definition corresponding to a four-finger left swipe gesture that is typically used for an accessibility operating mode. The second gesture recognizer has: a third event definition corresponding to a two-finger left swipe gesture that is typically used for the normal operating mode and a fourth event definition corresponding to the four-finger left swipe gesture that is typically used for the accessibility operating mode. When the internal state of the electronic device is set in a way such that the electronic device operates in the accessibility mode, the electronic device determines whether a four-finger left swipe gesture that satisfies the second event definition is selected for any other event recognizer with two or more event definitions (e.g., the second event gesture recognizer). If the four-finger left swipe gesture is not selected for any other event recognizer with two or more event definitions, the four-finger left swipe gesture is selected for the first gesture recognizer in the accessibility operating mode. As a result, the four-finger left swipe gesture is not selected for the second gesture recognizer, because the four-finger left swipe gesture is already selected for the first gesture recognizer. Instead, the two-finger left swipe gesture is selected for the second gesture recognizer, because the two-finger left swipe gesture is not selected for any other gesture recognizer with two or more event definitions including the first gesture recognizer. In another example, the actively involved views have the first gesture recognizer and a third gesture recognizer without the second gesture recognizer. The third gesture recognizer has the third event definition (corresponding to the two-finger left swipe gesture) that is typically used for the normal operating mode and a fifth event definition corresponding to a three-finger left swipe gesture that is typically used for the accessibility operating mode. In the accessibility operating mode, the three-finger left swipe gesture can be selected for the third gesture recognizer, because the three-finger left swipe gesture is not selected for any other gesture recognizer with two or more event definitions. 
     Although the examples above have been described with respect to multi-finger left swipe gestures, the methods described above apply to swipe gestures in any direction (e.g., a swipe-right gesture, swipe-up gesture, swipe-down gesture, and/or any diagonal swipe gesture) or gestures of any other kinds (e.g., tap gestures, pinch gestures, depinch gestures, etc.). 
     In some embodiments, processing the respective sub-event in accordance with the selected event definition includes ( 1026 ) displaying one or more views of a first software application distinct from the software that includes the view hierarchy (e.g., concurrently displaying at least a portion of user interface  712 - 6  including one or more views of the software and a portion of home screen  708 ,  FIG.  7 S ). 
     In some embodiments, the at least one event recognizer processes ( 1028 ) the respective sub-event by replacing the display of the one or more views of the view hierarchy with display of one or more views of a first software application (e.g., home screen  708 ,  FIG.  7 A ) distinct from the software that includes the view hierarchy. 
     In some embodiments, the at least one event recognizer processes ( 1030 ) the respective sub-event by: displaying in a first predefined area of a display in the electronic device a group of open application icons that correspond to at least some of a plurality of concurrently open applications; and concurrently displaying at least a subset of the one or more views of the view hierarchy (e.g., open application icons  5004  and at least a portion of user interface  712 - 6 ,  FIG.  7 H ). For example, the electronic device concurrently displays the group of open application icons and at least a subset of the one or more views of the view hierarchy in response to a three-finger swipe-up gesture in the normal operating mode and a four-finger swipe-up gesture in the accessibility operating mode. 
     In accordance with some embodiments,  FIG.  11    shows a functional block diagram of an electronic device  1100  configured in accordance with the principles of the invention as described above. The functional blocks of the device may be implemented by hardware, software, or a combination of hardware and software to carry out the principles of the invention. It is understood by persons of skill in the art that the functional blocks described in  FIG.  11    may be combined or separated into sub-blocks to implement the principles of the invention as described above. Therefore, the description herein may support any possible combination or separation or further definition of the functional blocks described herein. 
     As shown in  FIG.  11   , an electronic device  1100  includes a touch-sensitive display unit  1102  configured to receive touch inputs; and a processing unit  1106  coupled to the touch-sensitive display unit  1102 . In some embodiments, the processing unit  1106  includes an executing unit  1108 , a display enabling unit  1110 , a detecting unit  1112 , a delivering unit  1114 , an identifying unit  1116 , and a touch input processing unit  1118 . 
     The processing unit  1106  is configured to: execute at least a first software application and a second software application (e.g., with the executing unit  1108 ). The first software application includes a first set of one or more gesture recognizers, and the second software application includes one or more views and a second set of one or more gesture recognizers. Respective gesture recognizers have corresponding gesture handlers. The processing unit  1106  is configured to enable display of at least a subset of the one or more views of the second software application (e.g., with the display enabling unit  1110 , on the touch-sensitive display unit  1102 ). The processing unit  1106  is configured to, while displaying at least the subset of the one or more views of the second software application: detect a sequence of touch inputs on the touch-sensitive display unit  1102  (e.g., with the detecting unit  1112 ). The sequence of touch inputs includes a first portion of one or more touch inputs and a second portion of one or more touch inputs subsequent to the first portion. The processing unit  1106  is configured to, during a first phase of detecting the sequence of touch inputs: deliver the first portion of one or more touch inputs to the first software application and the second software application (e.g., with the delivering unit  1114 ); identify from gesture recognizers in the first set one or more matching gesture recognizers that recognize the first portion of one or more touch inputs (e.g., with the identifying unit  1116 ); and process the first portion of one or more touch inputs with one or more gesture handlers corresponding to the one or more matching gesture recognizers (e.g., with the touch input processing unit  1118 ). 
     In some embodiments, the processing unit  1106  is configured to detect the sequence of touch inputs (e.g., with the detecting unit  1112 ) while touch inputs in the first portion of one or more touch inputs at least partially overlap at least one of the displayed views of the second software application. 
     In some embodiments, the processing unit  1106  is configured to enable display of at least a subset of the one or more views of the second software application without displaying any view of the first software application (e.g., with the display enabling unit  1110 , on the touch-sensitive display unit  1102 ). 
     In some embodiments, the processing unit  1106  is configured to enable display of at least a subset of the one or more views of the second software application without displaying a view of any other application (e.g., with the display enabling unit  1110 , on the touch-sensitive display unit  1102 ). 
     In some embodiments, the processing unit  1106  is configured to, during a second phase of detecting the sequence of touch inputs, subsequent to the first phase: deliver the second portion of one or more touch inputs to the first software application without delivering the second portion of one or more touch inputs to the second software application (e.g., with the delivering unit  1114 ); identify from the one or more matching gesture recognizers a second matching gesture recognizer that recognizes the sequence of touch inputs (e.g., with the identifying unit  1116 ); and process the sequence of touch inputs with a gesture handler corresponding to the respective matching gesture recognizer (e.g., with the touch input processing unit  1118 ). 
     In some embodiments, the processing unit  1106  is configured to process the sequence of touch inputs with the gesture handler corresponding to the respective matching gesture recognizer by enabling display of one or more views of the first software application (e.g., with the display enabling unit  1110 , on the touch-sensitive display unit  1102 ). 
     In some embodiments, the processing unit  1106  is configured to process the sequence of touch inputs with the gesture handler corresponding to the respective matching gesture recognizer by replacing the display of the one or more views of the second software application with display of one or more views of the first software application (e.g., with the display enabling unit  1110 , on the touch-sensitive display unit  1102 ). 
     In some embodiments, the processing unit  1106  is configured to: concurrently execute the first software application, the second software application, and a third software application (e.g., with the executing unit  1108 ); and process the sequence of touch inputs with the gesture handler corresponding to the respective matching gesture recognizer by replacing the one or more displayed views of the second software application with one or more views of the third software application (e.g., with the display enabling unit  1110 , on the touch-sensitive display unit  1102 ). 
     In some embodiments, the processing unit  1106  is configured to: enable display of, in a first predefined area of the touch-sensitive display unit  1102 , a group of open application icons that correspond to at least some of a plurality of concurrently open applications (e.g., with the display enabling unit  1110 ); and enable concurrent display of at least a subset of the one or more views of the second software application (e.g., with the display enabling unit  1110 ). 
     In some embodiments, the first software application is an application launcher. 
     In some embodiments, the first software application is an operating system application. 
     In accordance with some embodiments,  FIG.  12    shows a functional block diagram of an electronic device  1200  configured in accordance with the principles of the invention as described above. The functional blocks of the device may be implemented by hardware, software, or a combination of hardware and software to carry out the principles of the invention. It is understood by persons of skill in the art that the functional blocks described in  FIG.  12    may be combined or separated into sub-blocks to implement the principles of the invention as described above. Therefore, the description herein may support any possible combination or separation or further definition of the functional blocks described herein. 
     As shown in  FIG.  12   , an electronic device  1200  includes a touch-sensitive display unit  1202  configured to receive touch inputs; and a processing unit  1206  coupled to the touch-sensitive display unit  1202 . In some embodiments, the processing unit  1206  includes an executing unit  1208 , a display enabling unit  1210 , a detecting unit  1212 , a determining unit  1214 , a delivering unit  1216 , and a touch input processing unit  1218 . 
     The processing unit  1206  is configured to execute at least a first software application and a second software application (e.g., with the executing unit  1208 ). The first software application includes a first set of one or more gesture recognizers, and the second software application includes one or more views and a second set of one or more gesture recognizers. Respective gesture recognizers have corresponding gesture handlers. The processing unit  1206  is configured to enable display of a first set of one or more views (e.g., with the display enabling unit  1210 ). The first set of one or more views include at least a subset of the one or more views of the second software application. The processing unit  1206  is configured to, while displaying the first set of the one or more views, detect a sequence of touch inputs on the touch-sensitive display unit (e.g., with the detecting unit  1212 ). The sequence of touch inputs includes a first portion of one or more touch inputs and a second portion of one or more touch inputs subsequent to the first portion. The processing unit  1206  is configured to determine whether at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs (e.g., with the determining unit  1214 ). The processing unit  1206  is configured to, in accordance with a determination that at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs: deliver the sequence of touch inputs to the first software application without delivering the sequence of touch inputs to the second software application (e.g., with the delivering unit  1216 ); determine whether at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the sequence of touch inputs (e.g., with the determining unit  1214 ). The processing unit  1206  is configured to, in accordance with a determination that at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the sequence of touch inputs, process the sequence of touch inputs with the at least one gesture recognizer in the first set of one or more gesture recognizers that recognizes the sequence of touch inputs (e.g., with the touch input processing unit  1218 ). The processing unit  1206  is configured to, in accordance with a determination that no gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs: deliver the sequence of touch inputs to the second software application (e.g., with the delivering unit  1216 ); and determine whether at least one gesture recognizer in the second set of one or more gesture recognizers recognizes the sequence of touch inputs (e.g., with the determining unit  1214 ). The processing unit  1206  is configured to, in accordance with a determination that at least one gesture recognizer in the second set of one or more gesture recognizers recognizes the sequence of touch inputs, process the sequence of touch inputs with the at least one gesture recognizer in the second set of one or more gesture recognizers that recognizes the sequence of touch inputs (e.g., with the touch input processing unit  1218 ). 
     In some embodiments, the sequence of touch inputs at least partially overlaps at least one of the one or more displayed views of the second software application. 
     In some embodiments, the processing unit  1206  is configured to enable display of the first set of one or more views without displaying any view of the first software application (e.g., with the display enabling unit  1210 , on the touch-sensitive display unit  1202 ). 
     In some embodiments, the processing unit  1206  is configured to enable display of the first set of one or more views without displaying a view of any other software application (e.g., with the display enabling unit  1210 , on the touch-sensitive display unit  1202 ). 
     In some embodiments, prior to the determination that at least one gesture recognizer in the first set of one or more gesture recognizers recognizes the first portion of one or more touch inputs, the processing unit  1206  is configured to concurrently deliver the first portion of one or more touch inputs to the first software application and the second software application (e.g., with the delivering unit  1216 ). 
     In some embodiments, the first software application is an application launcher. 
     In some embodiments, the first software application is an operating system application. 
     In some embodiments, the processing unit  1206  is configured to process the sequence of touch inputs with the at least one gesture recognizer in the first set of one or more gesture recognizers by enabling displaying one or more views of the first software application (e.g., with the display enabling unit  1208 , on the touch-sensitive display unit  1202 ). 
     In some embodiments, the processing unit  1206  is configured to process the sequence of touch inputs with the at least one gesture recognizer in the first set of one or more gesture recognizers by replacing the display of the first set of one or more views with display of one or more views of the first software application (e.g., with the display enabling unit  1208 , on the touch-sensitive display unit  1202 ). 
     In some embodiments, the processing unit  1206  is configured to concurrently execute the first software application, the second software application, and a third software application (e.g., with the executing unit  1208 ). The processing unit  1206  is configured to process the sequence of touch inputs with the at least one gesture recognizer in the first set of one or more gesture recognizers by replacing the first set of one or more views with one or more views of the third software application (e.g., with the display enabling unit  1210 , on the touch-sensitive display unit  1202 ). 
     In some embodiments, the processing unit  1206  is configured to: enable display of in a first predefined area of the touch-sensitive display unit  1202  a group of open application icons that correspond to at least some of a plurality of concurrently open applications (e.g., with the display enabling unit  1210 ); and concurrently display at least a subset of the first set of one or more views (e.g., with the display enabling unit  1210 ). 
     In accordance with some embodiments,  FIG.  13    shows a functional block diagram of an electronic device  1300  configured in accordance with the principles of the invention as described above. The functional blocks of the device may be implemented by hardware, software, or a combination of hardware and software to carry out the principles of the invention. It is understood by persons of skill in the art that the functional blocks described in  FIG.  13    may be combined or separated into sub-blocks to implement the principles of the invention as described above. Therefore, the description herein may support any possible combination or separation or further definition of the functional blocks described herein. 
     As shown in  FIG.  13   , an electronic device  1300  includes a display unit  1302  configured to display one or more views; a memory unit  1304  configured to store an internal state; and a processing unit  1306  coupled to the display unit  1302  and the memory unit  1304 . In some embodiments, the processing unit  1306  includes an executing unit  1308 , a display enabling unit  1310 , a detecting unit  1312 , an identifying unit  1314 , a delivering unit  1316 , and an event/sub-event processing unit  1318 . In some embodiments, the processing unit  1306  includes the memory unit  1304 . 
     The processing unit  1306  is configured to: execute software that includes a view hierarchy with a plurality of views (e.g., with the executing unit  1308 ); enable display of one or more views of the view hierarchy (e.g., with the display enabling unit  1310 , on the display unit  1302 ); and execute one or more software elements (e.g., with the executing unit  1308 ). Each software element is associated with a particular view, and each particular view includes one or more event recognizers. Each event recognizer has: one or more event definitions based on one or more sub-events, and an event handler. The event handler specifies an action for a target, and is configured to send the action to the target in response to the event recognizer detecting an event corresponding to a particular event definition of the one or more event definitions. The processing unit  1306  is configured to: detect a sequence of one or more sub-events (e.g., with the detecting unit  1312 ); and identify one of the views of the view hierarchy as a hit view (e.g., with the identifying unit  1314 ). The hit view establishes which views in the view hierarchy are actively involved views. The processing unit  1306  is configured to deliver a respective sub-event to event recognizers for each actively involved view within the view hierarchy (e.g., with the delivering unit  1316 ). At least one event recognizer for actively involved views in the view hierarchy has a plurality of event definitions, one of which is selected in accordance with the internal state of the electronic device, and the at least one event recognizer processes the respective sub-event (e.g., with the event/sub-event processing unit  1318 ) prior to processing a next sub-event in the sequence of sub-events in accordance with the selected event definition. 
     In some embodiments, the plurality of event definitions includes a first event definition corresponding to a first swipe gesture with a first number of fingers and a second event definition corresponding to a second swipe gesture with a second number of fingers distinct from the first number of fingers. 
     In some embodiments, the internal state includes one or more settings for an accessibility operating mode. 
     In some embodiments, a respective definition of the plurality of event definitions is selected for a respective event recognizer in accordance with the internal state of the electronic device and a determination that the respective event definition does not correspond to an event definition of any event recognizer for the actively involved views other than the respective event recognizer. 
     In some embodiments, two or more event recognizers for actively involved views in the view hierarchy each have a respective plurality of event definitions, and a respective event definition of the respective plurality of event definitions is selected for a respective event recognizer in accordance with the internal state of the electronic device and a determination that the respective event definition does not correspond to any event definition selected for any event recognizer with two or more event definitions other than the respective event recognizer. 
     In some embodiments, the processing unit  1306  is configured to process the respective sub-event in accordance with the selected event definition by enabling display of one or more views of a first software application distinct from the software that includes the view hierarchy (e.g., with the display enabling unit  1310 , on the display unit  1302 ). 
     In some embodiments, the processing unit  1306  is configured to process the respective sub-event by replacing the display of the one or more views of the view hierarchy with display of one or more views of a first software application distinct from the software that includes the view hierarchy (e.g., with the display enabling unit  1310 , on the display unit  1302 ). 
     In some embodiments, the processing unit  1306  is configured to process the respective sub-event by: enabling display of, in a first predefined area of the display unit  1302 , a group of open application icons that correspond to at least some of a plurality of concurrently open applications (e.g., with the display enabling unit  1310 ); and enabling concurrently display of at least a subset of the one or more views of the view hierarchy (e.g., with the display enabling unit  1310 ). 
     In some embodiments, the software is an application launcher. 
     In some embodiments, the software is an operating system application. 
     The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.

Metadata:
Filing Date: 20211029
Publication Date: 20230912
Grant Date: 20230912
Priority Date: 20090316
Inventors: SHAFFER, JOSHUA H.
KOCIENDA, KENNETH L.
CHAUDHRI, IMRAN A.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/04883", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/04883", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F9/542", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04808", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F9/451", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F9/542", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04808", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F9/451", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/017", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04883", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/017", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F9/451", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F9/542", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04808", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 44278478