title: How to use beginBackgroundTaskWithExpirationHandler for already running task in iOS
body: <p>In my app, I am uploading images to server from iPhone. While sync if user press home button, App will close.</p>
  
  <p>I want app must be running in background till sync finish.</p>
  
  <p>My question is: How can I add currently running task with "<code>beginBackgroundTaskWithExpirationHandler</code>"?</p>
  
  <p>Please share your ideas.</p>