UICollectionView+NSFetchedResultsController
This is an example of how to use the new UICollectionView with NSFetchedResultsController. The trick is to queue the updates made through the NSFetchedResultsControllerDelegate until the controller finishes its updates. UICollectionView doesn't have the same beginUpdates and endUpdates that UITableView has to let it work easily with NSFetchedResultsController, so you have to queue them or you get internal consistency runtime exceptions.
Setup
Just include the header and write your NSFetchedResultsControllerDelegate methods like this:
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
{
[self.collectionView addChangeForSection:sectionInfo atIndex:sectionIndex forChangeType:type];
}
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
newIndexPath:(NSIndexPath *)newIndexPath
{
[self.collectionView addChangeForObjectAtIndexPath:indexPath forChangeType:type newIndexPath:newIndexPath];
}
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
[self.collectionView commitChanges];
}Credit
This is built on idea by Ash Furrow with category idea taken from Derrick Hathaway. Then came Blake Watters with idea to use NSOperation and finally I added some stuff I encountered along the way.