title: How to get key of NSDictionary
body: <p>I'm using Firebase and getting a snapshot and when I print it I get this: </p>
  
  <pre><code>{
      "-KOx03Q1f1Tl9AiWxNlg" =     {
           message = ".";
           senderId = B6WI1xkEBXd4cwYkYFQRneEvPBV2;
      };
  }
  </code></pre>
  
  <p>I want to get the key, the value of <code>-KOx03Q1f1Tl9AiWxNlg</code> key. I can't figure out how to get it.  I can print it as! <code>NSDictionary</code> and it looks exactly the same so it seems to be in that form...but I didn't know <code>NSDictionary</code> items had a key or name like that.  Can anyone explain this?</p>