快速的firebase聊天对话

Question

我使用了这个模型：

import Foundation
class Chat {
var message: String?
var senderID: String
var receiverID: String
var timestamp : String

init(messageTextString: String?, senderIDNumber: String, receiverIDNumber: String, timeStampString: String){
    message = messageTextString
    senderID = senderIDNumber
    receiverID = receiverIDNumber
    timestamp = timeStampString
}
}

对于 ChatViewController：

func numberOfSections(in collectionView: UICollectionView) -> Int {
    return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int{
    return chats.count
}

  func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell{
     let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellIdentifier, for: indexPath) as! ChatCollectionViewCell    
     let senderIDNumber = Auth.auth().currentUser?.uid
        if chats[indexPath.row].senderID == senderIDNumber {
        if let chatsText = chats[indexPath.row].message{
            let size = CGSize(width: 250, height: 1000)
            let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
            let estimatedFrame = NSString(string: chatsText).boundingRect(with: size, options: options, attributes: [NSAttributedStringKey.font : UIFont.systemFont(ofSize: 18)], context: nil)
            cell.messageSend.frame = CGRect(x:8,y:0,width:estimatedFrame.width + 16, height:estimatedFrame.height + 20)
            cell.textBubbleView.frame = CGRect(x:0,y:0,width:estimatedFrame.width + 16 + 8, height:estimatedFrame.height + 20)
         //showOutgoingMessage(text: chats[indexPath.row].message)
    }
            cell.messageSend.text = chats[indexPath.row].message
    }
    else {
          /*cell.messageReceived.text = chats[indexPath.row].message */
            let chatsText = chats[indexPath.row].message
            let size = CGSize(width: 250, height: 1000)
            let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
            let estimatedFrame = NSString(string: chatsText!).boundingRect(with: size, options: options, attributes: [NSAttributedStringKey.font : UIFont.systemFont(ofSize: 18)], context: nil)
            cell.messageSend.frame = CGRect(x:view.frame.width - estimatedFrame.width,y:0,width:estimatedFrame.width + 16, height:estimatedFrame.height + 20)
            cell.textBubbleView.frame = CGRect(x:view.frame.width - estimatedFrame.width,y:0,width:estimatedFrame.width + 16 + 8, height:estimatedFrame.height + 20)
    }
    return cell
 }

@objc func collectionView(_ collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAt indexPath: IndexPath) -> CGSize {
if let chatsText = chats[indexPath.row].message {
    let size = CGSize(width: 250, height: 1000)
        let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
        let estimatedFrame = NSString(string: chatsText).boundingRect(with: size, options: options, attributes: [NSAttributedStringKey.font : UIFont.systemFont(ofSize: 18)], context: nil)
        return CGSize(width: view.frame.width, height: estimatedFrame.height + 20)
    }
    return CGSize(width: view.frame.width, height: 200)
}

func loadPosts() {
    let ref = Database.database().reference()
    let senderIDNumber = Auth.auth().currentUser?.uid
    ref.child("chats").queryOrdered(byChild: "senderID").queryEqual(toValue: senderIDNumber).observe(.childAdded) { (snapshot: DataSnapshot) in
        if  let dict = snapshot.value as? [String: Any] {
            let messageText = dict["message"] as! String
            let senderIDNumber = dict["senderID"] as! String
            let receiverIDNumber = dict["receiverID"] as? String
            let timestamp = dict["timestamp"] as? String
            let chat = Chat(messageTextString: messageText, senderIDNumber: senderIDNumber, receiverIDNumber: receiverIDNumber!, timeStampString: timestamp!)
            //append(post) to array
            self.chats.append(chat)
            print(self.chats)
           self.collectionView.reloadData()
        }
    }
}

 func loadPostsReceivedMessage() {
    let ref = Database.database().reference()
    ref.child("chats").queryOrdered(byChild: "receiverID").queryEqual(toValue: receiverIDNumber).observe(.childAdded) { (snapshot: DataSnapshot) in
        if  let dict = snapshot.value as? [String: Any] {
            let messageText = dict["message"] as! String
            let senderIDNumber = dict["senderID"] as! String
            let receiverIDNumber = dict["receiverID"] as? String
            let timestamp = dict["timestamp"] as? String
            let chat = Chat(messageTextString: messageText, senderIDNumber: senderIDNumber, receiverIDNumber: receiverIDNumber!, timeStampString: timestamp!)
            self.chats.append(chat)
            print(self.chats)
            self.collectionView.reloadData()
        }
    }
}

}

我希望能够区分传出和传入消息，但无法做到。我确实想过创建一个 inComing 布尔值来区分传出和传入消息；但不知道如何实施。 我需要帮助和建议，非常感谢

Answer 1

Firebase 无法查询！！！（尤其是多重排序）..需要迁移到 firestorm（firebase 存储的新 Beta 版）或使用 angular。

Answer 2

能够区分发送的消息和接收的消息就像向 Chat 对象添加属性一样简单，因此您可能会遇到这样的事情：

class Chat {
    var message: String
    var senderID: String
    var receiverID: String
    var timestamp : String
    var isFromCurrentUser: Bool = false // You'll only need to change this property if the message is from the current sender.

    init(messageTextString: String?, senderIDNumber: String, receiverIDNumber: String, timeStampString: String){
        self.message = messageTextString
        self.senderID = senderIDNumber
        self.receiverID = receiverIDNumber
        self.timestamp = timeStampString
    }
}

修改对象后，您需要查看获取数据的方式。我建议将 loadPosts() 重命名为 listenForChatItemAdded() 并将函数更改为以下内容：

注意：不需要使用查询。当您只有某组数据时，查询特别有用；在这里，您最好抓取数据，并在对象初始化后对其进行排序。

func loadPosts() {
    let ref = Database.database().reference()
    let senderIDNumber = Auth.auth().currentUser?.uid
    ref.child("chats").observe(.childAdded) { (snapshot: DataSnapshot) in
        if  let dict = snapshot.value as? [String: Any] {
            let messageText = dict["message"] as! String
            let senderIDNumber = dict["senderID"] as! String
            let receiverIDNumber = dict["receiverID"] as? String
            let timestamp = dict["timestamp"] as? String

            let chat = Chat(messageTextString: messageText, senderIDNumber: senderIDNumber, receiverIDNumber: receiverIDNumber!, timeStampString: timestamp!)

            let currentUserUID = Auth().auth().currentUser!.uid
            if senderID == currentUserUID {
                chat.isFromCurrentUser = true
            }

            //append(post) to array
            self.chats.append(chat)

            //after adding the new chat tot the array, sort the array
            let sorted = filtered.sorted { (chat1, chat2) -> Bool in
                return chat1.timestamp > chat2.timestamp
            }

            // update the current array with the sorted array
            self.chats = sorted

            // reload the collectionView
            self.collectionView.reloadData()
        }
    }
}

最后，只需检查我们创建的属性以确定您应该如何直观地设置单元格。我将创建 UICollectionViewCell 的两个子类。一个用于发送者，一个用于接收者。如果聊天是由当前用户发送的，则使用 sender 子类创建一个单元格，如果聊天是由其他人发送的，则使用 receiver 子类。

希望这会有所帮助， 干杯！