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# mainWindow

The app’s main window.

```
weak var mainWindow: NSWindow? { get }
```

## Discussion

The value in this property is `nil` when the app’s storyboard or nib file has not yet finished loading. It might also be `nil` when the app is inactive or hidden.

## See Also

[`isMainWindow`](/documentation/AppKit/NSWindow/isMainWindow)

A Boolean value that indicates whether the window is the application’s main window.


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