ios - 我的单元格正在复制以应用我对在线数据库所做的更改

Question

使用此代码，我能够获取我的数据库的快照并将数据加载到 tableView 中。但是，当我尝试对在线数据库进行更改时，我得到了应用更改的重复单元格，而不是应用此更改的正常单元格。

    // Create reference to databse
    ref = Database.database().reference()

    // Retrieve data from firebase database and listen for changes
    ref.child("Clubs").observe(.value, with: { (snapshot) in
        print("clubs: \(snapshot)")

        if(snapshot.exists()) {
            let array:NSArray = snapshot.children.allObjects as NSArray

            for obj in array {
                let snapshot:DataSnapshot = obj as! DataSnapshot
                if let childSnapshot = snapshot.value as? [String : AnyObject] {
                    print("myClubs: \(childSnapshot)")

                    if let clubName = childSnapshot["name"] as? String, let banner = childSnapshot["bannerImage"] as? String {
                        print(clubName)
                        print(banner)

                        let club = Club(name: clubName, image: banner)
                        print("new club success: \(club)")
                        self.nightClubs.append(club)
                    }
                }
            }

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

        }

    })

Answer 1

只要 Clubs 中的任何值发生变化，您就会在监听器中执行代码。该代码将俱乐部附加到 nightClubs 数组，但不清除它。您需要在重新填充之前清空数组:

// Retrieve data from firebase database and listen for changes
    ref.child("Clubs").observe(.value, with: { (snapshot) in
        print("clubs: \(snapshot)")
        self.nightClubs.removeAll() // empty array before adding values

        ...