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)