title: Getting .value observers on specific children from a firebase database?
body: <p>I've got a list of topics that users can subscribe to or not. On the home page, I'm displaying, in a tableview, the list of rooms a user has subscribed to. I don't know if I'm overcomplicating this, but I'm having a hard time understanding how to get live observers on all of those individual topics.</p>
  
  <p>My database looks like :</p>
  
  <pre><code> topics:
        stackoverflow:
           users: 50
           lastPost : 2384938943
        twitch: 
           users : 50
           lastPost : 209340932843
     users: 
         user1:
           favoritedRooms:
             twitch : true
             stackoverflow : true
  </code></pre>
  
  <p>So I'm able to get the list of favorited rooms from the current user and store that into an array. From there though, I"m not sure how to update my tableview if one of these rooms has a value update. If I do something like store the favorited topics in an array when I fetch them and then do something like</p>
  
  <pre><code> for topic in favoritedTopicNames {
     somereference.observe(.value) {
         //make a Topic object
        // append it to an array I'm basing my table off of and reloadData
       }   
  }
  </code></pre>
  
  <p>then I'm setting up individual .value observers for each topic. I can't do this because this means each time a topic's observer is called I'm only getting that ONE topic back, so I can't clear out my array, append and reload because I'll end up with only 1 topic. </p>
  
  <p>So basically my question is, if I need to first query a specific list of topics to observe that are a subset of my topics node, how do I keep a live feed going on those specific topics so that if the user count or lastPost numbers are changed, I can update my labels and keep the information live?</p>