Should CoreData inverse relationships be represented as retained properties?

Question

I have two entities (Session and User). Session entity has loggedInUser relationship to User entity. And the User entity has session inverse relationship to Session entity.

Xcode generates properties with retain attribute for both direct and inverse relationships. Is it ok from object graph point of view? My understanding is that reverse relationship should be represented as assign property.

Also, in the schema editor it's not visible which relationship is the main one (i.e. loggedInUser has session as its inverse, and session's inverse is loggedInUser).

Maybe I'm missing something?

Thanks.

Answer 1

Doesn't really explain why as such but the Apple docs for Core Data state

In addition to always being nonatomic, dynamic properties only honor retain or copy attributes—assign is treated as retain. You should use copy sparingly as it increases overhead. You cannot use copy for relationships because NSManagedObject does not adopt the NSCopying protocol, and it's irrelevant to the behavior of to-many relationships.

So by reading that even if you did set a relationship as assign it would be treated as retain