Open Radar

 
Summary:

Fetching on the main thread can’t help but block the main thread. Longer fetches block for longer.

To do a background fetch and return results to the main thread, it's necessary to use a separate NSManagedObjectContext and pass managed object IDs back to the main thread, which are then turned into managed objects.

I'd like to see an API that lets me write code like this:

[managedObjectContext performFetchInBackground:fetchRequest completion:^(NSArray *fetchedObjects) {
    
    // Do something with fetchedObjects.
    // On the main thread here.
    });
};