Append Firebase chat messages

问题

I am creating a chat app and I have a list of all the messages sent between two users in a table view cell. For example, I have four texts in total between the two users and so I have four cells. However, I would like to group the cells so that I only have one cell, because I the loggedInUser is only communicating with one person. No matter what I do, the messages will not append.

func loadData(){
if (FIRAuth.auth()?.currentUser) != nil{

FIRDatabase.database().reference().child("messages").observeSingleEvent(of: .value, with: { (snapshot:FIRDataSnapshot) in

let loggedInUserData = snapshot
if let postsDictionary = snapshot .value as? [String: AnyObject] {

for post in postsDictionary {
    let messages = post.value as! [String: AnyObject]
    for (id, value) in messages {
        let info = value as! [String: AnyObject]
        if let receiver = info["ReceiverId"] {
        print("\(id): \(receiver)")
       self.messages.Array(value)

        }

    }
    self.MessageTableView.reloadData()
}


}})}
}

As of now my app is displaying messages between two users like this:

I think the issue is in the self.messages.Array(value) I just need to append messages between the same two users but I can't find the right code

But I would like for a conversation between two users to be in one cell (append it)

This is what my cell looks like:

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "MessageCell", for: indexPath) as! MessageTableViewCell


    //Configure the cell


    print(messages[indexPath.row])
    let message = self.messages[indexPath.row] as! [String: AnyObject]
    if let seconds = message["timestamp"] as? Double {
        let timeStampDate = NSDate(timeIntervalSince1970: seconds)
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "hh:mm a"
        cell.Time.text = dateFormatter.string(from: timeStampDate as Date)
    }



    cell.Message.text = message["text"] as? String
   // cell.SellerName.text = message["ReceiverId"] as? String


  if let imageName =  message["ReceiverId"] as? String {

        let ref = FIRDatabase.database().reference().child("posts").child(imageName)

    ref.observeSingleEvent(of: .value, with: { (snapshot)
        in

        if let dictionary = snapshot.value as? [String: AnyObject]{
            for post in dictionary {
                let messages = post.value as! [String: AnyObject]
                for (id, value) in messages {

                cell.SellerName.text = messages["username"] as? String
                    if (messages["uid"] as? String) != nil {
                        let uidPoster = messages["uid"] as? String
                        let imageRef = FIRStorage.storage().reference().child((uidPoster)!+"/profile_pic.jpg")

                        imageRef.data(withMaxSize: 25 * 1024 * 1024, completion: { (data, error) -> Void in
                            if error == nil {

                                let image = UIImage(data: data!)
                                cell.UserPic.image = image

                                cell.UserPic.layer.cornerRadius = 30
                                cell.UserPic.clipsToBounds = true



                            }else {

                                print("Error downloading image:" )


                            }})}

                    self.messages.add(value)
                }
            }


        }

    })
    }

    return cell
}

my path to firebase message is:

FIRDatabase.database().reference().child("messages").child("(self.convoId!)").childByAutoId()

Here is my database structure:

回答1:

I will use a super simple example in my answer.

Given a structure

messages
   msg_0
      rec: "uid_0"
      send: "uid_1"
      msg: "msg from uid_0 to uid_1"
   msg_1
      rec: "uid_1"
      send: "uid_0"
      msg: "msg from uid_1 to uid_0"

Add a query observer to the messages node watching for any new messages (.childAdded) that have a rec: of uid_0.

var messagesArray = [String]()

func watch() {
    let messagesRef = self.ref.child("messages")
    let queryRef = messagesRef.queryOrdered(byChild: "rec").queryEqual(toValue: "uid_0")

    queryRef.observe(.childAdded, with: { snapshot in

        let msgDict = snapshot.value as! [String: Any]
        let msg = msgDict["msg"] as! String

        self.messagesArray = [] //erases the array
        self.messagesArray.append(msg) //adds this new message at index 0

        print(self.messagesArray) //print is just for example
        //normally call tableView.reloadData() which will refresh
        //  the cells in the tableView and display just once cell with
        //  the latest message in it
    })
}

You can extrapolate from this by storing the snapshot or the dictionary in the array so you know the message text and can use the send: user id to look up who sent the message.

If you run this code, the output will be any new message sent to uid_0; only the latest message will be displayed. If you have a tableView with the messagesArray as it's dataSource (which is normally how its done) then the tableView would be refreshed and only ever show the latest message for uid_0.

As a side note, .queryLimited(toLast:) could be leveraged here was well.