Cocoa Touch: When does an NSFetchedResultsController become necessary to manage a Core Data fetch?

Question

I\'m developing an iPhone application that makes heavy use of Core Data, primarily for its database-like features (such as the ability to set a sort order or predicate on fe

Answer 1

NSFetchedResultsController is an incredibly handy helper class for interfacing Core Data with your UITableViews. My recommendation would be to use it with every table view that has a Core Data backing. In every case I've used it for, it significantly reduced the amount of code I had to write.

Performance-wise, it can lead to a huge improvement as well. Rather than fetching in your entire data set, if you use -setFetchBatchSize: with the NSFetchRequest that you feed into the NSFetchedResultsController, you can do batched fetching where only the relevant data being displayed in your table view is fetched. Data no longer on display can also be removed from memory automatically (or so is my understanding).

For tables with moderate to large data sets, this can lead to a significant performance win. Apple engineers have been quoted as saying that for a 10,000 item database, this can reduce your startup time by over 80% and your memory usage by 50%.