title: Highlight part of text in UILabel
body: <p>in my application I have a <code>UILabel</code> with a lot of text inside. When the user performs a research I want to highlight the background under the text searched by the user.
  Here an example from "Preview" in MacOSX.</p>
  
  <p><img src="https://i.stack.imgur.com/aLooH.png" alt="enter image description here"></p>
  
  <p>The user searches <strong>silence</strong> and this word is highlighted in the text.</p>
  
  <p>Any ideas ?
  Thanks.</p>