Question

我在我的应用程序中遇到了一个非常有趣的问题。在查看用户配置文件页面时，我的tableview中的数据被拉出并打印到控制台中，但问题是我的信息不会加载到我的tablecell中。

如果我要退出当前标签然后返回个人资料页面，我的数据将被加载。我正在使用firebase来提取我的信息。

我希望第一次查看页面时数据存在。

ProfileViewController

    var cellId = "cell"
    var userGames = [Game]()
    var userCurrentGames = [Any]()

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.delegate = self
        tableView.dataSource = self

        tableView.register(ProfileGameCell.self, forCellReuseIdentifier: cellId)

    //I CALL MY FUNCTIONS UPON FIRST LOAD
        getCurrentUser()
        getUsersGames()

        }
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

    //I CALL FUCTIONS EVERY TIME THE VIEW LOADS INCASE DATA CHANGES
        getCurrentUser()
        getUsersInformation()
        getUsersGames()

    }

    func getUsersGames() {
        let ref = Database.database().reference()
        let current = getCurrentUser()

//I FIND ALL THE GAMES IN THE USERS REF AND APPEND THEIR KEY TO THE ARRAY
            ref.child("users").child(current).child("user games").observe(.value, with: {(snapshot) in
                if let snapshot = snapshot.children.allObjects as? [DataSnapshot] {
                    self.userCurrentGames = []
                    for snap in snapshot {
                        let gameKey = snap.key

                        print("SNAPSHOT DATAAA: \(gameKey)")
                        self.userCurrentGames.append(gameKey)
                    }
                }
            })
            displayUsersGames()
    }

func displayUsersGames() {
    let ref = Database.database().reference()
    self.userGames = []
//I FIND ALL THE GAMES AND APPEND THEM TO THE ACTUAL GAME ARRAY
    for i in userCurrentGames {
        ref.child("games").child("\(i)").observeSingleEvent(of: .value, with: { (gameSnap) in
            if let gameDict = gameSnap.value as? Dictionary<String, AnyObject> {
                let key = gameSnap.key
                let game = Game(postKey: key, gameData: gameDict)
                self.userGames.append(game)

                self.tableView.reloadData()
            }
        })
    }
}

表格视图功能

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let game = userGames[indexPath.row]
    if let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as? ProfileGameCell {
        cell.adminButton.tag = indexPath.row
        cell.configureUserGameCell(game: game)
        return cell
    } else {
        return ProfileGameCell()
    }
}

func numberOfSections(in tableView: UITableView) -> Int {
    return 1
}

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return userGames.count
}

Answer 1

问题非常明确：

observe异步工作 - 稍后会返回结果 - 因此userCurrentGames在调用displayUsersGames()时为空。

解决方案是将displayUsersGames()移至完成块

...   
ref.child("users").child(current).child("user games").observe(.value, with: {(snapshot) in
        if let snapshot = snapshot.children.allObjects as? [DataSnapshot] {
            self.userCurrentGames = []
            for snap in snapshot {
                let gameKey = snap.key

                print("SNAPSHOT DATAAA: \(gameKey)")
                self.userCurrentGames.append(gameKey)
            }
            self.displayUsersGames()
        }
    })

注意：

强制向下转动单元格

let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as! ProfileGameCell

代码不得崩溃。如果是这样，则会发现设计错误。

Swift 4：UITableViewCell在初始加载时不会显示数据，但会在第二次加载时加载

1 个答案: