Now that we’ve set up the app to work with the NSFetchedResultsController instead of just an array, we can leverage the methods embedded with the controller to help us. The view controller has built-in support for monitoring the data for changes through a delegate. We had set ourselves up as that delegate but never implemented the code to handle data changing.

Having the view completely reload when it detects a change can become cumbersome if you are dealing with a large amount of data; however, the FetchedResultsController delegate also has support built-in for notifying you of the specific cell that is changed, and you can modify just that. Check Apple’s documentation for more details.