title: How to get only action button share facebook from UIActivityViewController
body: <p>I have a case follows: </p>
  
  <ul>
  <li>In app, i create a UIButton, when click will show a popup share facebook like UIActivityViewController. But i don't known get popup share facebook from UIActivityViewController. I need help everybody. </li>
  </ul>
  
  <p>THANK YOU SO MUCH !!!</p>