ios - 如何从 UItableview 中删除单元格，当它在 onChildRemoved 方法中从 Firebase 中删除时？

Question

我正在用来自 Firebase 的数据填充我的 uitableview，当我从 Firebase 中删除数据时，它仍然显示。我不知道在我的 onChildRemoved 方法中放入什么来删除它。我已经搜索了很多次如何做到这一点，但我仍然卡住了!

这是我的代码:

 class class_custom_cell2: UITableViewCell {
    @IBOutlet weak var cc: UILabel!

    @IBOutlet weak var teacher: UILabel!
    @IBOutlet weak var rn: UILabel!

    @IBOutlet weak var id: UILabel!


 }

  class Home: UIViewController , UITableViewDelegate, UITableViewDataSource{
var classes2 = [Class]()
var pass1: String!
var pass2: String!
var pass3: String!
var pass4: String!
@IBOutlet weak var tb_Yourclasses: UITableView!


    override func viewDidLoad() {
        super.viewDidLoad()

   fetchClass2()

    }

func fetchClass2(){
   let userID = Auth.auth().currentUser!.uid

    print(userID)
  Database.database().reference().child("Users").child(userID)
.child("Classes").observe(.childAdded, with: { (snapshot) in
   print("1",snapshot)
        //need to get the child"class_info" from firebase
         let class_id = snapshot.value as? String
    print("2",class_id)

 Database.database().reference().child("Classes").child(class_id!)
.child("class_info").observe(DataEventType.value, with: { (snapshot) in
                print("2.5",snapshot)
            let postDict = snapshot.value as? [String : AnyObject] ?? [:]


            print("3", postDict)
                let class_object = Class(dictionary: postDict)
                    self.classes2.append(class_object)
                    //self.classes.append(class_object)


                    DispatchQueue.main.async(execute: {
                        self.tb_Yourclasses.reloadData()
                    })


            }, withCancel: nil)



    }, withCancel: nil)
    Database.database().reference().child("Users").child(userID).child("Classes").observe(.childRemoved, with: { (snapshot) in
//idk what to do here
        let id = snapshot.value as? String
    })

}  
    @objc func handleCancel() {
        dismiss(animated: true, completion: nil)
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        //print(classes2)
        return classes2.count

    }

   func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCell(withIdentifier: "cell2", for: indexPath) as! class_custom_cell2

        let data_class2 = classes2[indexPath.row]
    print(data_class2)
        cell.cc?.text = data_class2.date_clasname
        cell.teacher?.text = data_class2.teacher
        cell.rn?.text = data_class2.room_number
    cell.id?.text = data_class2.class_id
   return cell
    }
 func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    let indexPath = tableView.indexPathForSelectedRow!
    let currentCell = tableView.cellForRow(at: indexPath)! as! class_custom_cell2
    pass1 = currentCell.cc.text

    pass2 = currentCell.teacher.text
    pass3 = currentCell.rn.text
    pass4 = currentCell.id.text
performSegue(withIdentifier: "remove_detail", sender: self)
}
 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if (segue.identifier=="remove_detail") {
        let viewController = segue.destination as! removeClassDetail
        viewController.receivedClassName = pass1
        viewController.receivedTeacher = pass2

        viewController.receiveRoomNumber = pass3
        viewController.receiveClassID = pass4

    }
}
}

这是数据库结构:

{
 "Classes" : {

"-LiGRe3e1YF_HFrHKMgi" : {
  "Students" : {
    "xfDGLrXF4gP8AJAPtAPc4VMe9y72" : "xfDGLrXF4gP8AJAPtAPc4VMe9y72"
  },
  "class_info" : {
    "date_clasname" : "mm",
    "room_number" : "jjhh",
    "subject" : "Science",
    "teacher" : "mm",
    "uid" : "-LiGRe3e1YF_HFrHKMgi"
  }
},


  "Users" : {
"xfDGLrXF4gP8AJAPtAPc4VMe9y72" : {
  "Classes" : {
    "-LiGRe3e1YF_HFrHKMgi" : "-LiGRe3e1YF_HFrHKMgi",

  },
  "User_info" : {
    "email" : "c@gmail.com",
    "grade" : "2",
    "name" : "n",
    "uid" : "xfDGLrXF4gP8AJAPtAPc4VMe9y72"
     }
   }
  }
}

谢谢，如果您有任何问题，请告诉我!

Answer 1

希望对你有帮助

Database.database().reference().child("Users").child(userID).child("Classes").observe(.childRemoved, with: { (snapshot) in
    let id = snapshot.value as? String
    for i in 0..<classes2.count {
        if (id == classes2[i].class_id) {
            DispatchQueue.main.async(execute: {
                classes2.remove(at: i)
                self.tb_Yourclasses.reloadData()
            })
            return
        }
    }
})

如果你有任何问题请联系我