导航回 ViewController 时出现重复消息问题

Question

我有一个 ViewController 可以向用户显示更多信息，然后他们单击一个按钮并将它们发送到我的 messageView，它是一个 JSQ ViewController。 JSQViewController 使用集合视图类。当用户导航回到更多信息视图，然后点击按钮再次导航到消息视图时，集合视图复制了我的聊天气泡。我想我需要将某些东西重置为零，但我不确定要设置什么以及在哪里设置。这是我的代码：

import UIKit
import Firebase
import JSQMessagesViewController


// MARK: Properties
var messages = [JSQMessage]()
var outgoingBubbleImageView: JSQMessagesBubbleImage!
var incomingBubbleImageView: JSQMessagesBubbleImage!
let rootReference = FIRDatabase.database().referenceFromURL("myHTTPSLINK")
var messageReference: FIRDatabaseReference!
var dataBaseMessageRef: FIRDatabaseReference!


class ChatViewController: JSQMessagesViewController{


var userContacedID: String = ""

var userToBeChatted : String = ""

var userIsTypingRef: FIRDatabaseReference!

var usersTypingQuery: FIRDatabaseQuery!

private var localTyping = false
var isTyping: Bool {
    get {
        return localTyping
    }
    set {
        localTyping = newValue
        userIsTypingRef.setValue(newValue)
    }
}




override func viewDidLoad() {
    super.viewDidLoad()



    title = "Now Chatting With: " + userToBeChatted
    setupBubbles()


    // No avatars
    collectionView!.collectionViewLayout.incomingAvatarViewSize = CGSizeZero
    collectionView!.collectionViewLayout.outgoingAvatarViewSize = CGSizeZero

    messageReference = rootReference.child("messages")

    dataBaseMessageRef = messageReference.child("\(userToBeChatted)" + "\(FIRAuth.auth()?.currentUser?.displayName)")



    print ("This users being messaged is: ", userToBeChatted)


}



override func didPressSendButton(button: UIButton!, withMessageText text: String!, senderId: String!,
                                 senderDisplayName: String!, date: NSDate!) {

    let itemRef = dataBaseMessageRef.childByAutoId() // 1
    let messageItem = [ // 2
        "text": text,
        "senderId": senderId,
        "receiver" : userToBeChatted,
        "senderName": FIRAuth.auth()?.currentUser?.displayName,
        "receiverID": userContacedID
    ]
    itemRef.setValue(messageItem) // 3

    // 4
    JSQSystemSoundPlayer.jsq_playMessageSentSound()

    // 5
    finishSendingMessage()
}



override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)


    observeMessages()
    observeTyping()
}



override func viewDidDisappear(animated: Bool) {




    super.viewDidDisappear(animated)
}



override func collectionView(collectionView: JSQMessagesCollectionView!,
                             messageDataForItemAtIndexPath indexPath: NSIndexPath!) -> JSQMessageData! {
    return messages[indexPath.item]
}

override func collectionView(collectionView: UICollectionView,
                             numberOfItemsInSection section: Int) -> Int {
    return messages.count
}


override func collectionView(collectionView: JSQMessagesCollectionView!,
                             messageBubbleImageDataForItemAtIndexPath indexPath: NSIndexPath!) -> JSQMessageBubbleImageDataSource! {



    let message = messages[indexPath.item] // 1


    if message.senderId == senderId { // 2
        return outgoingBubbleImageView
    } else { // 3
        return incomingBubbleImageView
    }
}



override func collectionView(collectionView: JSQMessagesCollectionView!,
                             avatarImageDataForItemAtIndexPath indexPath: NSIndexPath!) -> JSQMessageAvatarImageDataSource! {
    return nil
}

private func setupBubbles() {
    let factory = JSQMessagesBubbleImageFactory()
    outgoingBubbleImageView = factory.outgoingMessagesBubbleImageWithColor(
        UIColor.jsq_messageBubbleBlueColor())
    incomingBubbleImageView = factory.incomingMessagesBubbleImageWithColor(
        UIColor.jsq_messageBubbleRedColor())
}


func addMessage(id: String, text: String) {
    let message = JSQMessage(senderId: id, displayName: FIRAuth.auth()?.currentUser?.displayName , text: text)
    messages.append(message)
}



override func collectionView(collectionView: UICollectionView,
                             cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = super.collectionView(collectionView, cellForItemAtIndexPath: indexPath)
        as! JSQMessagesCollectionViewCell

    let message = messages[indexPath.item]

    if message.senderId == senderId {
        cell.textView!.textColor = UIColor.whiteColor()
    } else {
        cell.textView!.textColor = UIColor.whiteColor()
    }

    return cell
}




private func observeMessages() {

     dataBaseMessageRef = messageReference.child("\(userToBeChatted)\(FIRAuth.auth()?.currentUser?.displayName as String!)")




    let messagesQuery = dataBaseMessageRef.queryLimitedToLast(25)

    messagesQuery.observeEventType(.ChildAdded, withBlock: { snapshot in
        let id = snapshot.value!["senderId"] as! String
        let text = snapshot.value!["text"] as! String
        self.addMessage(id, text: text)
        self.finishReceivingMessage()
    })
}


override func textViewDidChange(textView: UITextView) {
    super.textViewDidChange(textView)
    isTyping = textView.text != ""
}

private func observeTyping() {
    let typingIndicatorRef = rootReference.child("typingIndicator")
    userIsTypingRef = typingIndicatorRef.child(senderId)
    userIsTypingRef.onDisconnectRemoveValue()

    usersTypingQuery = typingIndicatorRef.queryOrderedByValue().queryEqualToValue(true)
    usersTypingQuery.observeEventType(.Value, withBlock: { snapshot in
        // You're the only one typing, don't show the indicator
        if snapshot.childrenCount == 1 && self.isTyping { return }

        // Are there others typing?
        self.showTypingIndicator = snapshot.childrenCount > 0
        self.scrollToBottomAnimated(true)
    })
}


}

Answer 1

在 viewDidAppear 之前 observeMessages() 插入 messages.removeAll() 或 messages = []

Answer 2

将 observeMessages() 从 viewDidAppear() 移动到 viewDidLoad()。

有同样的问题，并设法用上面的方法解决了它。

导航回 ViewController 时出现重复消息问题

Issue with Duplicate Messages When navigating back to ViewController

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