title: How do I parse a NSString?
body: <p>I have a string </p>
  
  <pre><code>https://gdata.youtube.com/feeds/api/videos?q=4s-PbMuNooo
  </code></pre>
  
  <p>I want to get string 4s-PbMuNooo. How do I parse a NSString?</p>