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# NSUndoManagerDidOpenUndoGroup

Posted whenever an undo manager opens an undo group.

```
static let NSUndoManagerDidOpenUndoGroup: NSNotification.Name
```

## Discussion

This notification originates in the implementation of the [`beginUndoGrouping()`](/documentation/Foundation/UndoManager/beginUndoGrouping()) method.

The notification object is the `NSUndoManager` object. This notification doesn’t contain a `userInfo` dictionary.

The system posts this notification on the actor, thread, or dispatch queue that calls [`beginUndoGrouping()`](/documentation/Foundation/UndoManager/beginUndoGrouping()).

---

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