title: NSDateFormatter parses two-digit year as 2046 instead of 1946 or 2040 instead of 1940
body: <p>I have a scenario where I'm getting a date string as "46-05-24" (yy-mm-dd), and I need to re-format the date as "1946-05-24". The <code>NSDateFormatter</code> interprets the string as "2046-05-24".</p>
  
  <p>I'm using this code:</p>
  
  <pre><code>    let dateFormatter = NSDateFormatter()
      dateFormatter.dateFormat = "yy-mm-dd"
      let gmt : NSTimeZone = NSTimeZone(abbreviation: "GMT")!
      dateFormatter.timeZone = gmt
      let dateFromString = dateFormatter.dateFromString(date as String)
      dateFormatter.dateFormat = "yyyy-mm-dd"
      if dateFromString != nil{
          let dateString = dateFormatter.stringFromDate(dateFromString!)
          print(dateString)
      }
  </code></pre>
  
  <p>Is there something I'm missing here?</p>