How to use NSColor? Where does it belong? How to reference it?

I want to use th开发者_如何学编程e keyboardFocusIndicatorColor inside my code but not sure where NSColor is. The documentation says AppKit.framework but when I try to link a library AppKit.framework does not exist.

NSColor *transBG = [[NSColor keyboardFocusIndicatorColor]

You tagged this question iOS so you should be using UIColor and the UIKit framework instead.