If the App Delegate's window property is nil
, the app creates a window for you.
To make a custom window, implement a window
getter in the App Delegate.
From the docs for App Delegate's window
property:
Implementation of this property is required if your app’s Info.plist file contains the UIMainStoryboardFile key. Fortunately, the Xcode project templates usually include a synthesized declaration of the property automatically for the app delegate. The default value of this synthesized property is nil, which causes the app to create a generic UIWindow object and assign it to the property. If you want to provide a custom window for your app, you must implement the getter method of this property and use it to create and return your custom window.