Structuring data for chat app in Firebase

Question

Im following Firebase guide to structuring data for a chat app. They suggest the structure as seen below.

{
  // Chats contains only meta info about each conver         


        

Answer 1

How do I structure my user data so that I can easily display a list of all of the chats they are part of and for each one of them display the last message and timestamp.

Change the chats structure a tad by adding users who are in the chat node

"chats": {
    "one": {
      "title": "Historical Tech Pioneers",
      "lastMessage": "ghopper: Relay malfunction found. Cause: moth.",
      "timestamp": 1459361875666
      users
       uid_1: true
       uid_3: true
    },
    "two": { ... },

Then you can deep query for all chats a particular user is part of - this will return the chats uid_3 is involved in

chatsRef.queryOrderedByChild("users/uid_3").queryEqualToValue(true)
     .observeSingleEventOfType(.Value, withBlock: { snapshot in

     //.Value can return multiple nodes within the snapshot so iterate over them
     for child in snapshot.children {
          let lastmsg = child.value["lastMessage"] as! String
          let timestamp = child.value["timestamp"] as! String
          print(lastmsg)
          print(timestamp)
     }     
})

Note that each firebase user has a discreet user id obtained when the user is created via auth.uid. This should (generally) be used as the key for each user.