Sets whether the next undo or redo action is discardable.
- iOS 5.0+
- macOS 10.7+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
Specifies if the action is discardable.
YESif the next undo or redo action can be discarded;
Specifies that the latest undo action may be safely discarded when a document can not be saved for any reason.
An example might be an undo action that changes the viewable area of a document.