Where can I find the source code of UIDatePicker of ios4

Where can I find the source code of  specific widget 开发者_如何学Cinside ios4?  

for exmaple , the code of UIDatePicker ,segment control ...

Thanks advance for your help.

BR,

camino

UIKit is not open source; the source code is not available.

As Jim said, the source code ad an UIKit element is not available because it isn't open source.
But if you are searching for source code that show how to use them, you can search on the Developer Site.
UICatalog source code is what are you looking for.
It shows how to use the most common UIKit's element, like buttons, pickers, alerts and other...