setActionIsDiscardable(_:)
Sets whether the next undo or redo action is discardable.
Declaration
func setActionIsDiscardable(_ discardable: Bool)Parameters
Discussion
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.
To find out if an undo group contains only discardable actions, look for the NSUndoManagerGroupIsDiscardableKey in the userInfo dictionary of the NSUndoManagerWillCloseUndoGroup.