NSManagedObjectContext Child/Parent - Child not removing registeredObjects

Question

I have 2 NSManagedObject contexts, one temporary and another that is primary. The temporary context has its parent context set to the primary context. I use them both in the following cases:

• When I create a "new" object, I create a new one with the temporary context. If the user hits "cancel" and decides not to create the new object, I simply delete the object from the managed object context and save that context.
• If the user saves this new object, I save the temporary context and then save the primary context to persist these changes. I use the "performBlock" methods and chain the saves, as is recommended by Apple and other Stackoverflow posts.
• If I'm editing an existing object, I keep it in the primary context during edits. If the user hits "cancel," I call "rollback" on the primary context, which discards all of the changes.

In these cases, everything seems to work fine. After the saves, the temporary context reports that it has 0 registered objects, and the primary context has an additional object.

However, there is a case where creating a "new" object includes another object which has a relationship to this new object. So for this object, I create the new object, create the "child" object, and set it on the parent. So there are 2 NSManagedObjects. I perform a "save" the same way - the temporary context is saved, and then the primary is saved afterward. The problem is that my temporary context is still stating that it has 2 registered objects after the save is completed. The primary object also states that it has 2, and they are all displaying correctly.

I can fix this by performing a "reset" on the temporary context after performing the "save" on the temporary context. However, this just doesn't seem right. Why should I have to do that? Why is my temporary context still reporting registered objects even after performing a save?

EDIT: I can also fix this by performing "refreshObject:object mergeChanges:NO" on the object from the temporary context after performing the save on the temporary context. This seems like the best solution for now (until someone can explain why I need to do this or why this is happening). My guess is that the objects are referring to each other, which is causing the objects to not release.

Answer 1

Why are you considered with the number of registered objects? Registered objects is simply a list of objects that the context is aware of. Since that context created those objects it would naturally continue to be aware of them even after the save. Core Data does not purge objects after a save.

Reads to me that it is working as intended.

Answer 2

When you perform save operation on MOC, It will save the object to parent MOC of persistent store. But object will still retained by MOC in memory.

By default, the references between a managed object and its context are weak. The exception to this rule is that a managed object context maintains a strong reference to any changed (inserted, deleted, and updated) objects until the pending transaction is committed (with a save:) or discarded (with a reset or rollback).

If you feel that this object is no longer need full for current future or alarms are generated (on the fly in a memory store), you would like to trim the graph object by turning every thing into a fault using "refreshObject:object mergeChanges:NO"