---
title: didOpenUndoGroup
framework: foundation
role: symbol
role_heading: Type Property
path: foundation/notificationcenter/messageidentifier/didopenundogroup
---

# didOpenUndoGroup

An identifier for a message about an undo manager having opened an undo group.

## Declaration

```swift
static var didOpenUndoGroup: NotificationCenter.BaseMessageIdentifier<UndoManager.DidOpenUndoGroupMessage> { get }
```

## Discussion

Discussion Use this identifier with NotificationCenter’s addObserver(of:for:using:) or messages(of:for:bufferSize:) methods to observe messages of type UndoManager.DidOpenUndoGroupMessage.

## See Also

### Identifying undo manager messages

- [willUndoChange](foundation/notificationcenter/messageidentifier/willundochange.md)
- [didUndoChange](foundation/notificationcenter/messageidentifier/didundochange.md)
- [willRedoChange](foundation/notificationcenter/messageidentifier/willredochange.md)
- [didRedoChange](foundation/notificationcenter/messageidentifier/didredochange.md)
- [checkpoint](foundation/notificationcenter/messageidentifier/checkpoint.md)
- [willCloseUndoGroup](foundation/notificationcenter/messageidentifier/willcloseundogroup.md)
- [didCloseUndoGroup](foundation/notificationcenter/messageidentifier/didcloseundogroup.md)