Need access to the image files of Interface Builder objects

Very simple question: I am designing a mock app screen by screen in the form of pictur开发者_高级运维es, and would like to use some of the graphics used for objects in Interface Builder (sliders, buttons, etc.). How can I access these files?

If you're interested in the artwork for the standard UI components you should check out:

https://github.com/0xced/UIKit-Artwork-Extractor

Cmd-shift-3 and cmd-shift-4. Or browse the internet.