O'Reilly logo

Learning iOS UI Development by Yari D'areglia

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Responder chain

An application can handle different kind of events thanks to responder objects. These objects implement specific methods that are useful to respond to one or more events. The UIResponder class is the base class where an interface for these events is defined; therefore, most of the classes that are directly exposed to user interaction are subclasses of UIResponder, such as UIView, UIViewController, UIControl, and even the UIApplication class.

A touch event is propagated through the application structure following an explicit path: the event is generated by the system and added into the event queue; the UIApplication singleton gets the topmost event and propagates it to the key window that, in turn, identifies the view where the touch ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required