title: iOS: Truncate a large string , and appending a suffix string
body: <p>I need to display some text in two lines , e.g.</p>
  
  <p>| a very large string string string |</p>
  
  <p>| string string  ... - a suffix string |</p>
  
  <p>The whole text contains two part</p>
  
  <ol>
  <li>a large description string, need be truncated</li>
  <li>"-a suffix string", won't be truncated</li>
  </ol>
  
  <p>How to implement it in iOS ?</p>