You can set the undo manager to nil to disable undo support. This provides a performance benefit if you do not want to support undo for a particular context, for example in a large import process—see Core Data Programming Guide.
If a context does not have an undo manager, you can enable undo support by setting one. You may also replace a context’s undo manager if you want to integrate the context’s undo operations with another undo manager in your application.
Removes everything from the undo stack, discards all insertions and deletions, and restores updated objects to their last committed values.
This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.