title: Error when trying to println an NSString from NSDictionary (JSON)
body: <p>There is something that I can't understand... I have this function :</p>
  
  <pre><code>func getDataByKey(key: String, jsonDict: NSDictionary) -&gt; NSString {
      for (name, value) in jsonDict {
          if name.isEqual(key) {
              println(value)
              return value as NSString
          }
      }
      return "-1"
  }
  </code></pre>
  
  <p>I get the result in another function, when it returns "-1" I can display it, the println also display the result well but when I try to display the value returned on the line "return value as NSString" my app shutdown with (lldb).</p>
  
  <p>Any idea of where it could come from ?</p>
  
  <p>Thanks in advance</p>