undoRedoItemGroup
The group that contains the undo/redo buttons that this view controller adds to the navigation bar.
Declaration
var undoRedoItemGroup: UIBarButtonItemGroup { get }Discussion
If you want undo and redo buttons to appear in your UIDocumentViewController, add an undoRedoItemGroup to the navigation bar and ensure that your custom UIDocument has an undo manager assigned to it. UIDocumentViewController sets the hidden property of this group, depending on the availability of an undo manager. It automatically enables or disables the buttons inside the group, as necessary.