Mac OS X Mac OS X has a layered system architecture in which increasingly complex sets of services and subsystems depend on and are built upon more fundamental systems. The most fundamental layer in Mac OS X is the Mach kernel environment, where basic control and access to hardware is provided for the operating system. Each of these application environments provide a unique set of frameworks, libraries, and services essential for the runtime execution of applications and programs developed with their respective APIs. Each of these application environments provides a unique solution for a unique problem. Frameworks and APIs Cocoa consists of two object-oriented frameworks called the Foundation and Application Kit.
Frameworks also have APIs for accessing the classes and functions.
That is, you can write Cocoa programs using either the Java language, or the Objective-C programming language. Objective-C is the native tongue of Cocoa, and as such I will focus on that as our language of choice. These will be covered in due course. What Objective-C lacks in basic functionality required to build modern software, Cocoa's Foundation Framework fills in. The Foundation Framework is a set of utility classes that provide basic functionality for things like string, text, number, and array handling.