Swift - Load information from Core Data faster

Question

Hey how to get big amount of information like 1000 rows without stuck? I try with this:

dispatch_async(dispatch_get_main_queue(), {
//here code
})

but when I executed the request self.context.executeFetchRequest it returns me fatal error: unexpectedly found nil while unwrapping an Optional value. I have an error and I have to add self. in front of the function.

    let queue:dispatch_queue_t = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
 dispatch_async(queue, { () -> Void in
                 //code
        })

but also I get the same error...

I use NSFetchRequest and I add the results in NSArray and I loop the results in for loop and in the loop I sort results in a dictionaries.

Answer 1

1000 records is not very much for Core Data. Just fetch them on the thread.

I would not advise to "sort results in a dictionaries". You should think how your app logic interacts with the data and simply fetch the objects you need from the Core Data persistent store.

For example, if you want to display 1000 lines in a table view, use `NSFetchedResultsController´ which is optimized for this sort of situation - so you will avoid memory and performance issues without any work.

If you really need threading with Core Data (which I doubt) I would advise not to start with GCD but to use Core Data's own concurrency APIs, such as performBlock and global queue child contexts. But most likely you won't have to worry about those.

Finally, your error is really referring to some code that you have not posted. It has to do with Swift's optionals. For example, if you declare a variable as type variable : String? (or you use an API that returns such a type), you can unwrap it with variable! if you are sure it is not nil . If it is nil you will get the above crash.