iOS: How do I add/remove a NSPredicate to my FetchedResultsController from a button press?

Question

I have a button that I currently have set up as a toggle. It currently only changes it's text when pressed. I am wanting to have it filter out entries in my uitableview though. I'm guessing I'd do that by adding a NSPredicate to my fetchedresultscontroller, but I'm unsure how to do this. Anyone know how I might be able to do this or send me in the correct direction if this is not the proper way of doing this task? Thanks!

Answer 1

On button click, you would be require to release the instance of fetchedresultscontroller (if in memory), as you would be require to re-create FetchRequest with Predicate in it.

After that, you could call execute api. As, fetchedresultscontroller will be required a new predicate.

Preferrable is to use 1 level of fetchedResultsController api call from Core Data. Because Fetching from DB is costly as compared to filtering the objects w.r.t already loaded objects in memory.

In your case, use fetchedresultscontroller with fetching all required apis, and as per toggle, just use predicate on in-memory array/records. This will improve performance and secondly, since the records will be core-data managed objects, so if they will be in no-more use, they could get faulted.