window

Instance Property

window

The window to use when presenting a storyboard.

 

Declaration

optional var window: UIWindow? { get set }

Discussion

This property contains the window used to present the app’s visual content on the device’s main screen. 

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.

 

developer.apple.com/documentation/uikit/uiapplicationdelegate/1623056-window

Apple Developer Documentation