AppKit.fx is included in the OS X SDK only, and provides all the classes and visual controls you need for creating Mac GUI applications. It is not available for iOS, watchOS or tvOS.

For legacy reasons, most of these classes share a common naming prefix with Foundation and start with NS*. Classes you will be working with include NSWindow, NSButton, NSTableView and the like.

All types from AppKit.fx are exposed in the AppKit Namespace.

Note: A Cocoa.framework (and matching .fx) exists in the OS X SDK. This framework is merely a bundle of Foundation and AppKit, and not to be confused with our general use of the term "Cocoa" to refer to the entire platform. Your projects can choose to either reference Cocoa.fx or Foundation.fx and AppKit.fx individually – the end result is the same.

Some recommended topics in Apple's excellent documentation are:

See Also