Written by Mattt December 29th, 2014 This article has been translated into: 中文 Cocoa is the de facto standard library of Objective-C, containing many of the essential frameworks for working in the language, such as Foundation, AppKit, and Core Data. Cocoa Touch is basically just Cocoa with UIKit substituted for AppKit, and is often used interchangeably with Cocoa to refer to the system frameworks