Have you ever wondered how the NSFetchedResultsController class does its magic? A fetched results controller seems to be magically notified whenever the result of its fetch request changes. The Core Data framework exposes several APIs that allow developers to replicate the behavior of the NSFetchedResultsController class.
In this tutorial, I show you how to leverage these APIs to observe a managed object context and be notified whenever an event takes place that your application is interested in.
Read this article on Cocoacasts.