title: UITextField get currently edited word
body: <p>I'm working on an autocompletion component and I have one problem that I would like to solve in some easy way.</p>
  
  <p>I want to support edits to autocompleted text, for example:</p>
  
  <pre><code> blablabl @usertag blablabl
  </code></pre>
  
  <p>If user goes back and edits @usertag string, I would like to start autocompletion when it's edited.</p>
  
  <p>Question is, how to get currently edited word from textfield. I thought about taking cursor position, seperate nsstring to word by " " (space) and count letters from first word to cursor position.</p>
  
  <p>Is there any easier way for doing that?</p>