Here it is a an document from Apple on iPhone programming guidelines and architecture to be followed:

Any iPhone app example you get hold of will use MVC design! MVC is so cruical to iPhone development.

Here are a few examples of how the Cocoa touch framework uses MVC:

  • UIViewController and subclasses (Controllers)
  • UIView/UIResponder/UIControl and subclasses (Views)
  • NSString/NSArray/NSDictionary/Core Data (Model)