title: How to know which index a child was added to an ordered FirebaseQuery
body: <p>Using Firebase and Swift SDK</p>
  
  <p>I just started with Firebase and wanted to display a list of Conversations ordered by last_update. The following query works fine :</p>
  
  <pre><code>let query = Database.database().reference().child("chat").child("channels").queryOrdered(byChild: "last_update")
  
  query.observe(DataEventType.childAdded) { (snapshot: DataSnapshot) in
      if let value = snapshot.value as? [String: Any?] {
          log.debug("added channel: \(snapshot.key) : \(value)")
          //add object to array, insertRow in tableview
      }
  }
  </code></pre>
  
  <p>The first time my view is loaded, each item arrives in the correct order specified by the query, so the display is ok. But if I create a new channel, it does appear at the end of the tableview, because I just add it at the end of the array and just call insertRow on my table view. My question is : is there any mecanism that give us the new inserted position of the DataSnapshot ?</p>
  
  <p>Same question for DataEventType.childMoved : we get to know that a snapshot has moved, but how to know where it has moved ??</p>