undoManager
The object that provides undo support for the context.
Declaration
var undoManager: UndoManager? { get set }Discussion
Enable undo support for a context by setting this property to an instance of UndoManager. This can be an undo manager that’s exclusive to the context, or an existing undo manager if you want to integrate the context’s undo operations with those of the rest of your app.
If your context uses an undo manager, you can realize a performance benefit by temporarily setting this property to nil when performing expensive operations on that context, such as importing a large number of objects.
The default value is nil.