I am developing an application which requires running a task in background. I am trying this by calling a method which will retrieve(download) data from web server through web services. this method will call some more methods which are in different view controller classes. Here when I tap on home button of device, the method is calling but no further execution of the remaining code.

This is the code I have written in

• (void)applicationDidEnterBackground:(UIApplication )application { UIApplication app = [UIApplication sharedApplication];

  UIBackgroundTaskIdentifier bgTask = 0; bgTask = [app beginBackgroundTaskWithExpirationHandler:^{ [app endBackgroundTask:bgTask]; bgTask = UIBackgroundTaskInvalid; }];

  // Start the long-running task and return immediately.
  

  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

      // Do the work associated with the task.
  
  
  NSString *updatekey = [[NSUserDefaults standardUserDefaults] objectForKey:@"updatesetting"];
  if([updatekey isEqualToString:@"enabled"])
  {
      DataSettingsView *periodicUpdate = [[DataSettingsView alloc] init];
      [periodicUpdate updateDataPeriodically];
          //[periodicUpdate viewDidLoad];
          //[periodicUpdate release];
  }
  
  
  [app endBackgroundTask:bgTask];
  bgTask = UIBackgroundTaskInvalid;
  

  });

}

some one please help me in this background execution of long tasks with some example of code.

Some help will appreciated and helpful to me.