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# boundsDidChangeNotification

A notification that posts when the view’s bounds rectangle changes to a new value independently of the frame rectangle.

```
class let boundsDidChangeNotification: NSNotification.Name
```

## Discussion

This notification posts only when the view’s [`postsBoundsChangedNotifications`](/documentation/AppKit/NSView/postsBoundsChangedNotifications) property is <doc://com.apple.documentation/documentation/Swift/true>.

The notification object is the `NSView` object whose bounds rectangle has changed. This notification does not contain a `userInfo` dictionary.

The following methods can result in notification posting:

- [`bounds`](/documentation/AppKit/NSView/bounds)
- [`setBoundsOrigin(_:)`](/documentation/AppKit/NSView/setBoundsOrigin(_:))
- [`boundsRotation`](/documentation/AppKit/NSView/boundsRotation)
- [`setBoundsSize(_:)`](/documentation/AppKit/NSView/setBoundsSize(_:))
- [`translateOrigin(to:)`](/documentation/AppKit/NSView/translateOrigin(to:))
- [`scaleUnitSquare(to:)`](/documentation/AppKit/NSView/scaleUnitSquare(to:))
- [`rotate(byDegrees:)`](/documentation/AppKit/NSView/rotate(byDegrees:))

Note that the bounds rectangle resizes automatically to track the frame rectangle. However, changes to the frame rectangle do not result in this bounds-changed notification.

To observe this notification using Swift concurrency, use [`NSView.BoundsDidChangeMessage`](/documentation/AppKit/NSView/BoundsDidChangeMessage).

---

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