title: How to show a waiting overlay in iOS project?
body: <p>I'm having a project I'm writing in iOS and Swift.</p>
  
  <p>I have a button that I press and then an action that takes around 2 seconds before the callback is called (and then I move to the next screen).</p>
  
  <p>I want to block the screen or show a waiting overlay, 
  or do something to block the user for those 2 seconds, 
  I don't want to open a new view with a spinner and then to move from that to the next one.</p>
  
  <p>How to handle that?</p>