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# didChangeExternallyNotification

Posted when the value of one or more keys changes due to incoming data from iCloud.

```
class let didChangeExternallyNotification: NSNotification.Name
```

## Discussion

If your app is running when iCloud delivers changes from another device, the system
generates this notification for your app. Use it to update your app’s content in
response to the new data.

The user info dictionary can contain additional data about the reason for the notification:

- When the [`NSUbiquitousKeyValueStoreChangeReasonKey`](/documentation/Foundation/NSUbiquitousKeyValueStoreChangeReasonKey) key is present, it indicates the
  reason why the key-value store changed. The value of this key is one of the constants
  [`NSUbiquitousKeyValueStoreServerChange`](/documentation/Foundation/NSUbiquitousKeyValueStoreServerChange), [`NSUbiquitousKeyValueStoreInitialSyncChange`](/documentation/Foundation/NSUbiquitousKeyValueStoreInitialSyncChange),
  [`NSUbiquitousKeyValueStoreQuotaViolationChange`](/documentation/Foundation/NSUbiquitousKeyValueStoreQuotaViolationChange), or [`NSUbiquitousKeyValueStoreAccountChange`](/documentation/Foundation/NSUbiquitousKeyValueStoreAccountChange).
- When the [`NSUbiquitousKeyValueStoreChangedKeysKey`](/documentation/Foundation/NSUbiquitousKeyValueStoreChangedKeysKey) key is present, its value is an
  array of strings, each of which contains the name of a key that changed.

To receive this notification, register for it shortly after launch. Specify the default
key-value store object as the object from which you want to receive notifications.

---

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