Learning Mobile App Development: A Hands-on Guide to Building Apps with iOS and Android

Views and Controllers

The user interface classes in iOS are contained in the UIKit framework. The UIKit framework contains a large number of classes that you can take advantage of in your apps. The classes are arranged in an inheritance hierarchy with the top class being UIView. This class describes a basic rectangle with width, height, background color, and so on. This class can contain subviews and may also have a parent view. One of the subclasses of UIView is UIWindow, which has been restricted to set its origin to the top left of the screen. Each iOS app has one UIWindow object that is created when the app launches. All other screens are subviews of UIWindow. Other subclasses of UIView include UILabel, UIScrollView, UINavigationBar, UITableCell ...