<!--
{
  "availability" : [
    "iOS: 5.0.0 -",
    "iPadOS: 5.0.0 -",
    "macCatalyst: 13.1.0 -",
    "tvOS: -",
    "visionOS: 1.0.0 -",
    "watchOS: -"
  ],
  "documentType" : "symbol",
  "framework" : "UIKit",
  "identifier" : "/documentation/UIKit/UIApplicationDelegate/window",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Property",
  "symbol" : {
    "kind" : "Instance Property",
    "modules" : [
      "UIKit"
    ],
    "preciseIdentifier" : "c:objc(pl)UIApplicationDelegate(py)window"
  },
  "title" : "window"
}
-->

# window

The window to use when presenting a storyboard.

```
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`](/documentation/UIKit/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.

For more information about the [UIMainStoryboardFile](https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/iPhoneOSKeys.html#//apple_ref/doc/uid/TP40009252-SW9) key, see [Information Property List Key Reference](https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Introduction/Introduction.html#//apple_ref/doc/uid/TP40009247).

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)