What is way to declare app delegate by Xcode project templates?

What is way to declare app delegate by Xcode project templates?

App delegate is declared as a subclass of UIResponder by Xcode project templates. If the UIApplication object does not handle an event, it dispatches the event to your app delegate for processing. For more information about the types of events, you can handle, see UIResponder Class Reference.

The UIResponder class defines an interface for objects that respond to and handle events.