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# didChangeBackingPropertiesNotification

A notification that the window object backing properties changed.

```
class let didChangeBackingPropertiesNotification: NSNotification.Name
```

## Discussion

The notification object is the `NSWindow` object whose backing properties changed. This notification contains a `userInfo` dictionary that has backing scale and color space information. See [NSWindowDidChangeBackingPropertiesNotification User Info Properties](/documentation/AppKit/nswindowdidchangebackingpropertiesnotification-user-info-properties) for the `userInfo` dictionary keys and values.

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

---

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