Ios Firebase嵌套解析

我有以下Firebase查询用于解析到我的tableView中

{
  "-LC8fVE90ovEFRQAhhdv" : {
    "description" : "Bu grupta arkadaşlar takılsınlar",
    "members" : [ "VSVmIF4o0ie2QMIcXdTDTcC8Hq93", "hJgM5tYU45VmjaMTzYAG4Yo3RyD2", "YrLEyhWf9KOIwoK2YN7HrzxpwMc2" ],
    "title" : "Takılmaca"
  },
  "-LC8wUR-11bX5FnjQ6Mk" : {
    "description" : "Hello",
    "members" : [ "VSVmIF4o0ie2QMIcXdTDTcC8Hq93", "hJgM5tYU45VmjaMTzYAG4Yo3RyD2", "nkwPkD2FeDZZFDnLunTe3D2EuQr2", "YrLEyhWf9KOIwoK2YN7HrzxpwMc2" ],
    "messages" : {
      "-LC9Pj9krCB4kZnXtXc8" : {
        "content" : "Its me",
        "senderId" : "YrLEyhWf9KOIwoK2YN7HrzxpwMc2"
      },"-LC9Pj9krCB4kasfXtXc8" : {
        "content" : "Who are you",
        "senderId" : "YrLEyhWf9KOIwoK2YN7HrzxpwMc2"
      }
}

我正在尝试使用以下代码获取内容和senderId

var groupMessages = [Message]()
REF_GROUPS.observeSingleEvent(of: .value) { (groups) in
    guard let groups = groups.children.allObjects as? [DataSnapshot] else { return }

    for group in groups {
        let groupss = group.value as? NSDictionary

        if let messages = groupss!["messages"] as? [String: Any] {

        }
    }            
    handler(groupMessages)
}

---

然而，我无法访问内容，因为messages对象是由LC9Pj9krCB4kZnXtXc8等随机标识符创建的。如何获取内容和senderId？

首先，不要在Swift中使用NSDictionary或NSArray，这会使事情变得复杂。其次，只需检查snapshot.exists，而不是为AllObject设置保护

组中的for group应替换为snapshot.children中的for child，并且该子对象本身将是一个DataSnapshot。见以下代码：

REF_GROUPS.observeSingleEvent(of: DataEventType.value) { (snapshot) in
     if snapshot.exists() {
         var allMessages: Array<Dictionary<String, String>> = []
            for child in snapshot.children {
                let childSnapshot = child as! DataSnapshot
                guard let dictValue = childSnapshot.value as? Dictionary<String, Any>, let messages = dictValue["messages"] as? Dictionary<String, Any> else {continue}
                if let array = Array(messages.values) as? Array<Dictionary<String, String>> {
                    allMessages.append(contentsOf: array)
                }
            }

            /// All messages into single array
            print(allMessages)

            /// All senderIds
            let senderIds = allMessages.map({$0["senderId"]!})
            print(senderIds)

            /// Unique senderIds
            let uniqueSenderIds = Array(Set(senderIds))
            print(uniqueSenderIds)

            /// Grouping the senderId with messages
            var finalDict: Dictionary<String, [String]> = [:]
            for data in allMessages {
                guard let senderId = data["senderId"], let content = data["content"] else {continue}
                if var oldValue = finalDict[senderId] {
                    oldValue.append(content)
                }
                else {
                    finalDict[senderId] = [content]
                }
            }
            print(finalDict)

            /// Inbuilt Dictionary grouping function
            let dictionary = Dictionary(grouping: allMessages, by: {$0["senderId"]!})
            print(dictionary)
}

输出：senderIds

输出：uniqueSenderIds

产出：最终产出

产出：最终产出

---

我不知道你为什么要获取所有组的内容，但我建议你通过组->组ID->消息引用获取数据，并为该引用设置一个侦听器，以便在收到新消息时通知应用程序。

谢谢，它工作得很好。事实上，我需要获取特定用户发送的所有消息，这就是为什么我要遍历所有组，但我也要记住您的建议。最后，如何从该数组中提取senderId？@AtalayAsa我已编辑了答案。如果您需要所有组，请创建一个全局变量并将数组附加到该对象中。它给了我一个错误，如类型“Any”在映射函数中没有下标成员。在哪里？let array=Arraymessages.values是您正在使用的数组吗？是的，它是数组let array=Arraymessages.values，但错误发生在数组.map{$0[senderId]！}行中。

[["content": "Its me", "senderId": "YrLEyhWf9KOIwoK2YN7HrzxpwMc2"],["content": "Who are you", "senderId": "YrLEyhWf9KOIwoK2YN7HrzxpwMc2"]]

["YrLEyhWf9KOIwoK2YN7HrzxpwMc2", "YrLEyhWf9KOIwoK2YN7HrzxpwMc2"]

["YrLEyhWf9KOIwoK2YN7HrzxpwMc2"]

["YrLEyhWf9KOIwoK2YN7HrzxpwMc2": ["Its me", "Who are you"]]

["YrLEyhWf9KOIwoK2YN7HrzxpwMc2": [["content": "Its me", "senderId": "YrLEyhWf9KOIwoK2YN7HrzxpwMc2"], ["content": "Who are you", "senderId": "YrLEyhWf9KOIwoK2YN7HrzxpwMc2"]]]