FireBase中的observeEventType（FEventType.ChildAdded）不会刷新我的视图

Question

我尝试使用firebase在两个客户端之间创建聊天 首先进入视图我下载最后50条消息： 这里是代码：

current_room_id_url.queryLimitedToLast(50).queryOrderedByChild("date").observeSingleEventOfType(FEventType.Value) { (snapshot:FDataSnapshot!) -> Void in

            if let values = snapshot.value as? NSDictionary{
                for item in values {
                    print(item)
                    if !self.keys.contains(snapshot.key){
                        self.keys.append(item.key as! String)

                        if let message = item.value as? NSDictionary{
                            let date = message["date"] as! NSTimeInterval
                            let receiveSenderID = message["senderId"] as! String
                            let displayName = message["senderDisplayName"] as! String
                            self.createAvatar(receiveSenderID, senderDisplayName: displayName, color: UIColor.jsq_messageBubbleGreenColor())
                            let jsqMessage = JSQMessage(senderId: receiveSenderID , senderDisplayName: displayName, date: NSDate(timeIntervalSince1970: date), text: message["message"] as! String)
                            self.messages.append(jsqMessage)
                        }
                    }
                }
                //self.collectionView?.reloadData()
                self.messages.sortInPlace({ ($0.date.compare($1.date) == NSComparisonResult.OrderedAscending)})
                self.finishReceivingMessageAnimated(true)
            }
        }

之后我想在RealTime中发送所有消息：我正在使用该功能：

 current_room_id_url.queryLimitedToLast(1).observeEventType(.ChildAdded) { (snapshot:FDataSnapshot!) -> Void in
        if !self.keys.contains(snapshot.key){
            self.keys.append(snapshot.key)
            if let message = snapshot.value as? NSDictionary{
                let date = message["date"] as! NSTimeInterval
                let receiveSenderID = message["senderId"] as! String
                let receiveDisplayName = message["senderDisplayName"] as! String
                self.createAvatar(receiveSenderID, senderDisplayName: receiveDisplayName, color: UIColor.jsq_messageBubbleGreenColor())
                let jsqMessage = JSQMessage(senderId: receiveSenderID, senderDisplayName: receiveDisplayName, date: NSDate(timeIntervalSince1970: date), text: message["message"] as! String)
                self.messages.append(jsqMessage)
                if receiveSenderID != self.senderId{
                    JSQSystemSoundPlayer.jsq_playMessageReceivedSound()
                }
            }
            self.finishReceivingMessageAnimated(true)
        }
    } 

当我尝试使用debreakpoint调试时，我看到Im只有在我退出并返回视图时才进入第二个功能，而显然当我在chatRoom时我需要它... 谢谢！