A method for displaying information on a touch screen of a mobile device, the method comprising: determining, at the mobile device, a type of a cover (200a, 200b, 200c) of the mobile device based on a category Identifier, ID, of the cover received from the cover, wherein the category ID includes information about a position and a size of a fixed screen viewing portion of the cover; detecting reception of a call at the mobile device while the cover is in a closed state; in response to the detection of the reception of a call, entering a call-receiving state and displaying, on the touch screen, a call-receiving screen corresponding to the closed state of the cover, wherein the call-receiving screen corresponding to the closed state of the cover is configured to fit a position and size of the fixed screen viewing portion; detecting a trigger input for controlling the mobile device to enter a call execution state while the mobile device is in a call-receiving state and the cover is in the closed state; in response to detecting the trigger input, entering into a call execution state and displaying, on the touch screen, a call execution screen corresponding to the closed state of the cover, wherein the call execution screen corresponding to the closed state of the cover is configured to fit the position and size of the fixed screen viewing portion; detecting an open state of the cover; and in response to detecting the open state of the cover while displaying the call execution screen corresponding to the closed state of the cover, displaying, on the touch screen, a call execution screen corresponding to the open state of the cover, wherein the call execution screen corresponding to the open state of the cover is configured to fit a size of the touch screen, wherein the mobile device includes a member that forms a voltage based on magnetic properties, and a separation of a front portion of the cover from the mobile device is detected based on a voltage formed by the member, and wherein detecting an open state of the cover comprises detecting separation of the front portion of the cover from the mobile device. determining, at the mobile device, a type of a cover (200a, 200b, 200c) of the mobile device based on a category Identifier, ID, of the cover received from the cover, wherein the category ID includes information about a position and a size of a fixed screen viewing portion of the cover; detecting reception of a call at the mobile device while the cover is in a closed state; in response to the detection of the reception of a call, entering a call-receiving state and displaying, on the touch screen, a call-receiving screen corresponding to the closed state of the cover, wherein the call-receiving screen corresponding to the closed state of the cover is configured to fit a position and size of the fixed screen viewing portion; detecting a trigger input for controlling the mobile device to enter a call execution state while the mobile device is in a call-receiving state and the cover is in the closed state; in response to detecting the trigger input, entering into a call execution state and displaying, on the touch screen, a call execution screen corresponding to the closed state of the cover, wherein the call execution screen corresponding to the closed state of the cover is configured to fit the position and size of the fixed screen viewing portion; detecting an open state of the cover; and in response to detecting the open state of the cover while displaying the call execution screen corresponding to the closed state of the cover, displaying, on the touch screen, a call execution screen corresponding to the open state of the cover, wherein the call execution screen corresponding to the open state of the cover is configured to fit a size of the touch screen, wherein the mobile device includes a member that forms a voltage based on magnetic properties, and a separation of a front portion of the cover from the mobile device is detected based on a voltage formed by the member, and wherein detecting an open state of the cover comprises detecting separation of the front portion of the cover from the mobile device.