UndoManager.WillCloseUndoGroupMessage
A message that an undo manager sends before closing an undo group.
Declaration
struct WillCloseUndoGroupMessageOverview
The undo manager posts this message after you call endUndoGrouping(). Because this is a “will”-style message, the undo manager sends the message before it closes the undo group.
Observe this message with the identifier willCloseUndoGroup, or specify its type directly to the addObserver(of:for:using:) method. The Subject of this message type is UndoManager.
This message interoperates with the notification NSUndoManagerWillCloseUndoGroup. The system notifies observers of the message when the NotificationCenter posts the notification. Similarly, the system notifies observers of the notification when it posts the message.