Creating a new NSManagedObject within an NSPersistentDocument refuses to save even though undo shows as possible

I have a开发者_运维问答 CoreData / NSPersistentDoc app. It works fine.

I added a new entity to the MOM, and updated the version.

Now, when I create new instances of that Entity inside the MOC, the "Save" menu item remains disabled until/unless I create any instances of the old Entities that were already in the app.

The red dot button on titlebar correctly goes black to show that the document has changed - but OS X / NSDocument refuses to acknowledge this - it is impossible to do a Save.

Any ideas?

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I found the cause / solution - it was my own bug, but this answer may help others with similar issues.

I was using Apple's official approach for enabling the Copy/Paste menu items (by implementing validateMenuItem), and returning true/false for copy and paste at the right times.

And I was returning NSPersistentDocument's implementation for everything else (which included Save, although I didn't see that).

Then, when I added my new NSManagedObject, I added a sub-view, and sub-view-controller, and I delegated the validateMenuItem to this - i.e. so that it could handle it's own copy/paste status.

...but I had no code path for "if it's not copy paste, and it's not handled by the child, and it's not handled by my NSPersistenDocument subclass ... then hand it to NSPersistentDocument to decide"...

...and so the Save menuitem was never being enabled.