Make app always call applicationWillTerminate

AppDelegate.swift

  func applicationDidEnterBackground(application: UIApplication) {
    // Create a pseudo background task to system call applicationWillTerminate when app enter background
    // Default system will not call applicationWillTerminate when app enter background
    // applicationWillTerminate only called when user close app in app switcher or some special cases of system
    bgTask = application.beginBackgroundTaskWithExpirationHandler({ () -> Void in
      application.endBackgroundTask(self.bgTask)
      self.bgTask = UIBackgroundTaskInvalid
    })

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) { () -> Void in
      self.bgTask = UIBackgroundTaskInvalid
      application.endBackgroundTask(self.bgTask)
    }
  }

# Thanks A lot save my day .

This code for Swift 3

var bgTask : UIBackgroundTaskIdentifier!

func applicationDidEnterBackground(_ application: UIApplication) {
        // Create a pseudo background task to system call applicationWillTerminate when app enter background
        // Default system will not call applicationWillTerminate when app enter background
        // applicationWillTerminate only called when user close app in app switcher or some special cases of system
        bgTask = application.beginBackgroundTask(expirationHandler: { () -> Void in
            application.endBackgroundTask(self.bgTask)
            self.bgTask = UIBackgroundTaskInvalid
        })
        
        DispatchQueue.global(qos : .background).async() { () -> Void in
            self.bgTask = UIBackgroundTaskInvalid
            application.endBackgroundTask(self.bgTask)
        }
    }

Hello, could you please explain why we should dispatch on other queue task completion?
@quangtqag

    DispatchQueue.global(qos : .background).async() { () -> Void in
          self.bgTask = UIBackgroundTaskInvalid
          application.endBackgroundTask(self.bgTask)
      }