Cocoa and Cocoa Touch are the application development environments for Mac OS X and iOS, respectively. Both Cocoa and Cocoa Touch include the Objective-C run time and two core frameworks:
Cocoa, which includes the Foundation and AppKit frameworks, is used for developing applications that run on Mac OS X.
Cocoa Touch, which includes Foundation and UIKit frameworks, is used for developing applications that run on iOS.
Note: The term “Cocoa” has been used to refer generically to any class or object that is based on the Objective-C runtime and inherits from the root class, NSObject. The terms “Cocoa” or “Cocoa Touch” are also used when referring to application development using any programmatic interface of the respective platforms.