Run methods in background on certain intervel

Question

• (void)applicationWillResignActive:(UIApplication *)application {

  NSLog(@"to background");

  UIApplication *app = [UIApplication sharedApplication];

  // Request permission to run in the background. Provide an // expiration handler in case the task runs long. NSAssert(bgTask == UIBackgroundTaskInvalid, nil);

  bgTask = [app beginBackgroundTaskWithExpirationHandler:^{ // Synchronize the cleanup call on the main thread in case // the task actually finishes at around the same time. dispatch_async(dispatch_get_main_queue(), ^{

      if (bgTask != UIBackgroundTaskInvalid)
      {
          [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.
  [self performSelector:@selector(hai) withObject:nil afterDelay:30];
  
  NSLog(@"App staus: applicationDidEnterBackground");
  
  dispatch_async(dispatch_get_main_queue(), ^{
      if (bgTask != UIBackgroundTaskInvalid)
      {
          [app endBackgroundTask:bgTask];
          bgTask = UIBackgroundTaskInvalid;
      }
  });
  

  });

}