Swift NSFetchedResultsController

gistfile1.swift

 var fetchedResultsController: NSFetchedResultsController {
        if _fetchedResultsController != nil {
            return _fetchedResultsController!
            }

            let fetchRequest = NSFetchRequest()
            // Edit the entity name as appropriate.
            let entity = NSEntityDescription.entityForName(CPCommentObject.entityName(), inManagedObjectContext: NSManagedObjectContext.managedObjectContextForMainThread())
            fetchRequest.entity = entity

            // Set the batch size to a suitable number.
            fetchRequest.fetchBatchSize = 20

            // Edit the sort key as appropriate.
            let sortDescriptor = NSSortDescriptor(key: "date", ascending: false)
            let sortDescriptors = [sortDescriptor]

            fetchRequest.sortDescriptors = [sortDescriptor]

            // Edit the section name key path and cache name if appropriate.
            // nil for section name key path means "no sections".
            let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: NSManagedObjectContext.managedObjectContextForMainThread(), sectionNameKeyPath: nil, cacheName: nil)
            aFetchedResultsController.delegate = self
            _fetchedResultsController = aFetchedResultsController

            var error: NSError? = nil
            if !_fetchedResultsController!.performFetch(&error) {
                // Replace this implementation with code to handle the error appropriately.
                // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                //println("Unresolved error \(error), \(error.userInfo)")
                abort()
            }
            
            return _fetchedResultsController!
    }    
    var _fetchedResultsController: NSFetchedResultsController? = nil