iOS Firebase 实时数据库：我无法读取数据

Question

我是一名使用 Swift 语言学习 iOS 应用开发的学生。 使用 Firebase 实时数据库存在困难。

此错误代码：

<块引用>

线程 1：“[ setValue:forUndefinedKey:]：此类不符合关键成员的关键值编码。”

这是源代码：

import UIKit
import Firebase

class ViewController: UIViewController {
    
    var ref:DatabaseReference!
    
    override func viewDidLoad() {
        super.viewDidLoad()
               
        ref = Database.database().reference()
        ref.child("data").child("0").observeSingleEvent(of: .value, with: { snapShot in
                    let versionDic = snapShot.value as? Dictionary<String, AnyObject>
                    
                    let cafeDbData = DbCafeData()
                    cafeDbData.setValuesForKeys(versionDic!)
                   
                    print("[address] : \(cafeDbData.address)")
                    print("[end] : \(cafeDbData.end)")
                    print("[help] : \(cafeDbData.help)")
                    print("[member] : \(cafeDbData.member)")
                    print("[nummem] : \(cafeDbData.nummem)")
                    print("[start] : \(cafeDbData.start)")
                    print("[url] :  \(cafeDbData.url)")
                    print("[x] : \(cafeDbData.x)")
                    print("[y] : \(cafeDbData.y)")
                
                })
    }
}

另一个数据脚本：

import Foundation

class DbCafeData: NSObject {
    
    var address: String
    var end: String
    var help: String
    var member: String
    var nummem: String
    var start: String
    var url: String
    var x: String
    var y: String
    
    var kakao: String
    var twit: String
    var version: String
    var versioncode: Int
    
    init(address:String, end:String,
         help:String, member:String,
         nummem:String, start:String,
         url: String, x: String,
         y: String,
         kakao: String, twit: String,
         version: String, versioncode: Int) {
        
        self.address       = address
        self.end       = end
        self.help       = help
        self.member       = member
        self.nummem       = nummem
        self.start    = start
        self.url    = url
        self.x    = x
        self.y    = y
        self.kakao    = kakao
        self.twit    = twit
        self.version    = version
        self.versioncode    = versioncode
    }
    
    convenience override init() {
        self.init(address: "", end: "",
                  help: "", member: "",
                  nummem: "", start: "",
                  url: "", x: "",
                  y: "", kakao: "",
                  twit: "", version: "",
                  versioncode: 0)
    }
}

帮我解决这个问题！