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我目前正在创建一个消息传递应用程序，它可以从Firebase获取消息和相应的用户详细信息，并将它们加载到tableview上。我面临的问题是，一旦我开始检索用户详细信息，消息就会以错误的顺序显示，因为（我认为）与'Messages'数组相比，'Users'数组的填充顺序错误。

loadMessages功能：

func loadMessages() {

    // Grab all messages from assocated group ID from group-messages table
    Api.groupMessages.observeGroupMessages(groupId: self.groupId) { (messageId) in

        // After grabbing all message ID's, then grab the message details from the messages table
        Api.message.observeMessages(messageId: messageId, onSuccess: { (message) in

            print("1: \(message.senderId)")

            // Grab the user who sent the corresponding message based on senderId then update the message avatar
            Api.user.observeUser(withId: (message.senderId)!) { (user) in
                print("2: \(user.userId)")

                self.messages.append(message)
                self.users.append(user)

                DispatchQueue.main.async {
                    self.tableView.reloadData()
                }
            }

        })
    }

}

observeMessages功能：

func observeMessages(messageId: String, onSuccess: @escaping (Message) -> Void) {
    MESSAGE_REF.child(messageId).observeSingleEvent(of: .value, with: { (snapshot) in

        if let dict = snapshot.value as? [String: Any] {
            let message = Message.transformMessage(dict: dict)
            onSuccess(message)
        }

    })
}

observeUser功能：

func observeUser(withId userId: String, onSuccess: @escaping (User) -> Void) {
    USER_REF.child(userId).observeSingleEvent(of: .value, with: { (snapshot) in
        if let dict = snapshot.value as? [String: Any] {
            let user = User.transformUser(dict: dict)
            onSuccess(user)
        }
    })
}

消息类：

class Message {
    var senderId: String?
    var messageText: String?
}

extension Message {
    static func transformMessage(dict: [String: Any]) -> Message {
        let message = Message()
        message.messageText = dict["messageText"] as? String
        message.senderId = dict["senderId"] as? String
        return message
    }  
}

用户类

class User {
    var userId: String?
    var avatar: String?
}

extension User {
    static func transformUser(dict: [String: Any]) -> User {
        let user = User()
        user.userId = dict["userId"] as? String
        user.avatar = dict["avatar"] as? String
        return user
    }
}

打印数组时的结果

1: Optional("LClE82Z4msa5BwfNamCH6oBK1QI2")
1: Optional("LX6n4dL888hN5BsbPuLcFjWVWVw1")
1: Optional("LClE82Z4msa5BwfNamCH6oBK1QI2")
1: Optional("LX6n4dL888hN5BsbPuLcFjWVWVw1")
1: Optional("LX6n4dL888hN5BsbPuLcFjWVWVw1")

2: Optional("LClE82Z4msa5BwfNamCH6oBK1QI2")
2: Optional("LClE82Z4msa5BwfNamCH6oBK1QI2")
2: Optional("LX6n4dL888hN5BsbPuLcFjWVWVw1")
2: Optional("LX6n4dL888hN5BsbPuLcFjWVWVw1")
2: Optional("LX6n4dL888hN5BsbPuLcFjWVWVw1")

提前致谢！

Tableview以错误的顺序显示

0 个答案: