title: Android Services equivalent in iOS Swift
body: <p>I am looking for something that is equivalent to <code>Services</code> in <code>Android</code>. As far as I have searched I haven't found anything useful. I found <code>Background Fetch</code> but according to my understanding it cannot be used long processes.<br>
  Here is what I want to use it for.<br>
  fetch a list of twitter user ids from our web server then auto-follow those usernames in background. As there are limits in Twitter API, so the process will be long possibly 3-4 hours. Is this possible on iOS?</p>