swift - 无法将“NSTaggedPointerString”类型的值转换为“NSDictionary”

Question

当我启动我的应用程序时，我收到一个红色错误：线程 1：信号 SIGABRT并在分析中显示：无法将类型“NSTaggedPointerString”（0x10dc70598）的值转换为“NSDictionary”（0x10dc708b8）。代码：

func fetchDataFromServer(callback: @escaping (Room) -> ()) {
    DataService.dataService.ROOM_REF.observe(.childAdded) { (snapshot) in

        print("FOUND ROOM "+snapshot.key)

        let room = Room(key: snapshot.key, snapshot: snapshot.value as! Dictionary<String, AnyObject>)
        callback(room)
    }

一点JSON：

{
  "rooms" : {
    "-LRjiSQjXY4OkfQLRpCZ" : {
      "caption" : "Potatis",
      "thumbnailUrlFromStorage" : "gs://ilapp-   a1429.appspot.com/KLabp9zlfgZZ78dPQ9Eysrc9C6r2/564386764"
},

标签： swiftfirebasefirebase-realtime-database