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

# checkpoint

An identifier for a message about an undo manager reaching a checkpoint.

## Declaration

```swift
static var checkpoint: NotificationCenter.BaseMessageIdentifier<UndoManager.CheckpointMessage> { 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.CheckpointMessage.

## 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)
- [didOpenUndoGroup](foundation/notificationcenter/messageidentifier/didopenundogroup.md)
- [willCloseUndoGroup](foundation/notificationcenter/messageidentifier/willcloseundogroup.md)
- [didCloseUndoGroup](foundation/notificationcenter/messageidentifier/didcloseundogroup.md)