title: iOS: Keep an app running like a service
body: <p>In iOS, how would I instruct the OS to keep my app running even if it is no longer in the foreground?</p>
  
  <ul>
  <li><a href="https://itunes.apple.com/us/app/skype-for-iphone/id304878510?mt=8" rel="noreferrer">Skype</a></li>
  <li><a href="https://itunes.apple.com/us/app/viber/id382617920?mt=8" rel="noreferrer">Viber</a></li>
  <li><a href="https://itunes.apple.com/us/app/empatica-realtime/id702791633?mt=8" rel="noreferrer">Empatica</a></li>
  <li><a href="https://itunes.apple.com/us/app/zenly-locate-your-friends/id838848566?mt=8" rel="noreferrer">Zenly</a></li>
  </ul>
  
  <p>And many more apps does this.</p>