Marks the end of an undo group.
- iOS 3.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
All individual undo operations back to the matching
begin message are grouped together and reversed by a later
undo message. Undo groups can be nested, thus providing functionality similar to nested transactions. Raises an
NSInternal if there’s no
begin message in effect.