Swift Background Fetch

BackgroundFetch.swift

Step 1: Enable capabilities "background fetch"

Step2 : Setup AppDelegate.swift 


    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        let settings = UIUserNotificationSettings(forTypes: UIUserNotificationType.Alert, categories: nil)
        UIApplication.sharedApplication().registerUserNotificationSettings(settings)
        UIApplication.sharedApplication().setMinimumBackgroundFetchInterval(UIApplicationBackgroundFetchIntervalMinimum)
        return true;
     

    }

Step 3: Register application event in AppDelegate.swift, to register completion handler


 
    func application(application: UIApplication, performFetchWithCompletionHandler completionHandler: (UIBackgroundFetchResult) -> Void) {
        println("Complete");
        completionHandler(UIBackgroundFetchResult.NewData)
        
        getData();
        
    }
    
    func getData() -> Void{
        var url = "http://api.rottentomatoes.com/api/public/v1.0/lists/movies/box_office.json?apikey=xxxxxx&limit=20";
        var request = NSURLRequest(URL: NSURL(string: url));
        
        NSURLConnection.sendAsynchronousRequest(request,queue: NSOperationQueue.mainQueue()) {
            (response: NSURLResponse!, data: NSData!, error: NSError!) -> Void in
            var moviesResult = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil) as NSDictionary;
            var movies: [NSDictionary]=[];
            movies = moviesResult["movies"] as [NSDictionary];
            var localNotification:UILocalNotification = UILocalNotification()
            localNotification.alertAction = "Testing notifications on iOS8"
            localNotification.alertBody = "Movie Count : \(movies.count)"
            localNotification.fireDate = NSDate(timeIntervalSinceNow: 1)
            UIApplication.sharedApplication().scheduleLocalNotification(localNotification)
        }
        
        
    }

Your performFetchWithCompletionHandler is incorrect. According to this code, the completionHandler gets called before your getData(); it is likely your getData() will never run.

You should be passing the completionHandler as a parameter to getData() (must be the last parameter if you have more than one) and then called inside your NSURLConnection.sendAsynchronousRequest callback once its work is done.

No, daniel u are interpreting it wrong, mate

@vipulbansal please explain?

@RameshRM @SirobChilokin From Apple docs:

When this method is called, your app has up to 30 seconds of wall-clock time to perform the download operation and call the specified completion handler block. In practice, your app should call the completion handler block as soon as possible after downloading the needed data. If you do not call the completion handler in time, your app is terminated.

In this context, 'this method' is referring to application(_:performFetchWithCompletionHandler:), not the completion handler.

Edit: Tagged the wrong guy at the top :) The answer from @daniel-goldman is correct.

@daniel-goldman @bstien Can we please have a correct version of the code? Thanks in advance :)

This ia for swift 3 not 4
what to do?

Though this is all quite old, for anyone else wondering about @daniel-goldman comment, getData() should be changed over to

func getData(_ completion: () -> Void) { completion() }