title: How to startForeground() without showing notification?
body: <p>I want to create a service and make it run in the foreground. </p>
  
  <p>Most example codes have notifications on it. But I don't want to show any notification. Is that possible? </p>
  
  <p>Can you give me some examples? Are there any alternatives? </p>
  
  <p>My app service is doing mediaplayer. <strong>How to make system not kill my service except the app kill it itself</strong> (like pausing or stopping the music by button).</p>