title: Create same visual effect as when muting/unmuting iPhone (black rounded square with icon)
body: <p>I don't know the proper name for the effect I want to achieve, but it's the black rounded square with an icon and title that appears briefly in the center of the screen when you mute/unmute the phone or use the volume buttons.</p>
  
  <p>I've seen apps with the same effect but with a spinning activity indicator for the icon, or a checkmark and "Done" as the title.  I'd like to achieve both of these effects and also one with a custom icon and title.</p>
  
  <p>Is there a built-in way to do this?  (I'm having trouble searching documentation without having a clue what it's called.)</p>
  
  <p>If a built-in way does not exist, how should I create this effect?</p>