CoreData limit related entities batch size

Question

I ran into a really simple CoreData issue but it seems hard to solve. Writing a simple chat app where every user has many messages.

class CoreUser: NSManaged         


        

Answer 1

A fetch request always returns the objects from the managed object context. You cannot fetch "modified" objects, e.g. CoreUser objects with a "restricted" relationship to CoreMessage.

But what you can do instead is fetch the CoreMessage objects related to the given user:

let fetchRequest = NSFetchRequest(entityName: "CoreMessage")
fetchRequest.predicate = NSPredicate(format: "owner.id == %@", nodeId)

and now you can add a fetch limit to restrict the number of retrieved messages:

fetchRequest.fetchLimit = 20

together with a suitable sort descriptor.