title: NSDateFormatter returns nil in swift and iOS SDK 8.0
body: <p>I am reading the tutorial provided by Raywenderlich, <a href="http://www.raywenderlich.com/83963/ios-8-tutorials-now-available" rel="noreferrer">Chapter 29 What’s New with Testing</a>, and run into a strange problem.</p>
  
  <p>Following is the code in the tutorial converting a string into date:</p>
  
  <pre><code>// Convert date string to date.
  let dateFormatter = NSDateFormatter()
  dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss zzz"
  var date: NSDate? = dateFormatter.dateFromString(dateString)
  </code></pre>
  
  <p>The dateString is of the form </p>
  
  <pre><code>2014-06-21 14:56:00 EST
  </code></pre>
  
  <p>However, the date variable is always nil.</p>
  
  <p>NOTE: when playing this code in the playground, it works properly, as the image shows:</p>
  
  <p><img src="https://i.stack.imgur.com/oQkuB.png" alt="enter image description here"></p>
  
  <p>I am working in iOS SDK 8.0. Is it a bug of the SDK?</p>
  
  <hr>
  
  <p>Updated</p>
  
  <p>I am testing using a latest iPod Touch with iOS 8.</p>