Open Radar

 
Area:
Core Data

Summary:
NSFetchedResultsController doesn't detect cache invalidation after inserting new object and saving related NSManagedObjectContext.

Steps to Reproduce:
1. Run the attached sample project. In a nutshell project allows you to manage Parent with Children: insert new Parent, list children of a given Parent, insert new Child to the Parent, move one Child to another Parent. Last operation (move) triggers a bug.
2. Tap Add at the Parents screen to insert new Parent.
3. Navigate to newly inserted Parent and add one Child.
4. Return back to Parents screen and add yet another Parent.
5. Navigate to the inserted parent screen to make sure its content is empty and force creation of NSFetchedResultsController's cache for this parent.
6. Return to the first Parent children screen and tap at the Child. This will allow you to change parent of the child. Tap other parent.
7. Navigate to the second Parent children' screen.

Expected Results:
Second Parent' screen should display Child moved from first Parent. I've read the Core Data documentation and found no mention of such behaviour. Thus considering it's a bug.

Actual Results:
Second Parent' screen displays nothing.

Additional Information:
Bug will not reproduce if you:
— don't save context after changing the parent (see. `UpdateParentViewController.m:86`)
— don't use NSFetchedResultsController's cache

I've checked underlying SQLite database and it contains all updates I made with child.

Version/Build:
Version 10.0 (10A255), iOS 12 SDK

Configuration:
N/A