Question

Every app has an application delegate.

Where in the code that we specify/register that “SomeClass” (subclass of UIApplicationDelegate) is a delegate of my application ?

Answer 1

If you use Storyboarding, this is done in main.m with the line:

UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));

If the fourth argument to UIApplicationMain() is not nil, the function will create an instance of the specified class and assign it as the UIApplication object’s delegate.

If you don’t use Storyboarding, the connection is made in MainWindow.xib where the application delegate object is created and connected as the delegate of the File’s Owner (which is the UIApplication instance, which in turn is created by the UIApplicationMain() function).