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# ALAssetsLibraryChangedNotification

Sent when the contents of the assets library have changed from under the app that is using the data.

```
extern NSString * const ALAssetsLibraryChangedNotification;
```

## Discussion

In iOS 4.0, the notification’s <doc://com.apple.documentation/documentation/Foundation/NSNotification/object> is `nil`. In iOS 4.1 and later, the notification object is the library object that posted the notification.

In iOS 6.0 and later, the user information dictionary describes what changed:

- If the user information dictionary is `nil`, reload all assets and asset groups.
- If the user information dictionary an empty dictionary, there is no need to reload assets and asset groups.
- If the user information dictionary is not empty, reload the effected assets and asset groups. For the keys used, see [Notification Keys](/documentation/AssetsLibrary/notification-keys).

This notification is sent on an arbitrary thread.

---

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