I have a hard time to understand the difference between the NSFetchRequest and the NSFetchResultsController. I also don't know in which situation I would choose which one of them.
I would be really happy, if someone could explain it in simple terms.
NSFetchRequest is a simple static description of the set of NSManagedObjects you would like to grab from your NSManagedObjectContext.
NSFetchResultsController helps manage the objects fetched for use in an (NS/UI) TableView/CollectionView. The set of objects returned by an NSFetchRequest can change as objects are edited/inserted/deleted in your NSManagedObjectContext. NSFetchResultsController will help you track these changes.
NSFetchResultsController is configured with an NSFetchRequest.