I foolishly deleted it. I deleted the file that contained different versions within it.
I can revert to an old snapshot but I’ve done work since then.
Is it possible to revert to one of my archives or can I only submit/share from there?
I can still run the application, but I need to make changes to the database.
Xcode compiles .xcdatamodels into .moms. From the Organiser window you can use ‘Distribute…’ to ‘Export as Xcode Archive’. Do that, locate the archive file, right click and select ‘Show Package Contents’. In there navigate to Products/Applications to find your application. Show the package contents of that and in there should be either your .mom file directly or a bunch of them in a .momd folder if you’re using a versioned model. Grab the .moms you want.
Then activate the Xcode schema editor and from the menu bar select Editor->Import… . You should be able to import a .mom from there, recreating your Core Data schema.