iOS5 NSFetchedResultsController not getting delete updates

Question

I have a NSFetchedResultsController tied to my main managed object context. It is in charge of keeping data for a table view in my main view.

I have an NSOperation running on a background thread that refreshes/deletes the managed objects that the fetched results controller is keeping track of. I create a child context (private concurrency type / parent = main managed object context) in the nsoperation and insert/delete objects. When it is finished, it saves its context, as well as the parent context.

What's interesting and very frustrating is that this works fine in iOS 6. When I insert or delete objects, my fetched results controller is notified of the changes and everything works as expected. However, on iOS 5, everything works except for deletes. The fetched results controller is not notified of a delete. However... if I manually refresh the fetched results controller (making it nil and refetching the same predicate) then it will show the expected result.

Also, when I register for change/save notifications on the main context, I can see that the user info dictionary contains the objects that I've deleted... even in iOS 5!

One issue that I thought it may be, but I don't think holds because I've removed the factors, is that this object is in a many to one relationship with another object. The object I am deleting/inserting is an "employee" and it has a relationship with a "department". The employee is set to nullify and the department is set to cascade.

As I said, this works fine in iOS6 but not in iOS5.

Any tips would be very helpful.

Answer 1

This bug is due to saving to the persistent store. This child context saves itself, then calls perform block on it's parent, the main managed object context. When the main managed object context saves, it triggers a background context to write to the persistent store. When I removed the background context save, the fetched results controller updated as expected.

Something interesting that I found that was probably causing this was that the managed object was leaking every time I tried saving to the store. Not exactly sure how to fix this yet, but it's good to know the reason for it.