Swift 2.0 Asynchronous Fetch Request

AsyncFetchRequest.swift

 func getAllEvents(sortedByDate:Bool = false, sortAscending:Bool = true) -> Array<Event> {
        print("getAllEvents")
        
        var fetchedResults:Array<Event> = Array<Event>()
        
        let minionManagedObjectContextWorker:NSManagedObjectContext = NSManagedObjectContext.init(concurrencyType: NSManagedObjectContextConcurrencyType.PrivateQueueConcurrencyType)
        minionManagedObjectContextWorker.parentContext = self.mainContextInstance
        
        let fetchRequest = NSFetchRequest()
        let entity = NSEntityDescription.entityForName("Event", inManagedObjectContext: minionManagedObjectContextWorker)
        fetchRequest.entity = entity
        
        //Create sort descriptor to sort retrieved Events by Date, ascending
        if sortedByDate {
            let sortDescriptor = NSSortDescriptor(key: "date",
                ascending: sortAscending)
            let sortDescriptors = [sortDescriptor]
            fetchRequest.sortDescriptors = sortDescriptors
        }
        
        let asyncFetch = NSAsynchronousFetchRequest(fetchRequest: fetchRequest) {
            (result:NSAsynchronousFetchResult!) -> Void in
            
            if result.finalResult!.count > 0 {
                print("async res:\(result.finalResult?.count)")

                fetchedResults = result.finalResult! as! [Event]
            }
            NSLog("Done.\(fetchedResults[0].title)")
        }
        
          //Execute Fetch request
        minionManagedObjectContextWorker.performBlock {
            do {
               try minionManagedObjectContextWorker.executeRequest(asyncFetch) as! NSAsynchronousFetchResult
            } catch let fetchError as NSError {
                print("retrieveById error: \(fetchError.localizedDescription)")
                fetchedResults = Array<Event>()
            }
        }
        
        return fetchedResults
    }