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# showDetailTargetDidChangeNotification

Posted when a split view controller is expanded or collapsed.

```
nonisolated class let showDetailTargetDidChangeNotification: NSNotification.Name
```

## Discussion

When a view controller is using [`show(_:sender:)`](/documentation/UIKit/UIViewController/show(_:sender:)) or [`showDetailViewController(_:sender:)`](/documentation/UIKit/UIViewController/showDetailViewController(_:sender:)), it may need to know when a split view controller higher in the view hierarchy has changed. This notification is sent when a split view controller expands or collapses. The object of this notification is the view controller that caused the change.

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