I have a problem I'm not exactly sure how to phrase well enough to find previous discussions. Hoping this hasn't been done to death, but please point me to previous discussions if that's the case.
I have my Core Data stack set up to migrate step-wise across versions when I deploy a new model version. This is working great. However, I can only reliably get the migration to run when there are non-trivial differences between model versions (e.g., added a new non-optional property to an entity). Otherwise, the auto-migration takes over.
In the cases where auto-migration qualifies, any migration policy or mapping model I provide seems to be ignored. How can I get the migration to acknowledge a custom NSEntityMigrationPolicy so I can do transformations on the data the user has already persisted?
Thanks!