title: Unable to create NSDate from string
body: <p>I have this code in Playground, and <code>date</code> is always nil. </p>
  
  <pre><code>let str = "2015-12-07T22:26:37.624Z"
  let formatter = NSDateFormatter()
  formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSS"
  let date = formatter.dateFromString(str)
  </code></pre>
  
  <p>The date string is retrieved from my server, which is always in GMT+0. </p>