通过导航后退按钮传递数据

Question

我处于这种情况:

我通过准备segue将4个数组从进度表传递到细节练习,它工作正常!当我尝试将数据从详细运动控制器传递回进度表控制器时,问题就开始了.我想使用默认导航后退按钮返回父视图.实际上我正在使用这个代码,但它不起作用,数据从子视图传递到父视图,但我无法在进度表中看到结果,似乎我需要刷新,但我也尝试了reloadData在viewDidLoad之后,它不起作用.有什么建议吗？谢谢.

override func viewWillDisappear(animated : Bool) {
    super.viewWillDisappear(animated)

    if (self.isMovingFromParentViewController()){
        print("n'drio")

        let historyView = self.storyboard!.instantiateViewControllerWithIdentifier("historyView") as! HistoryTableViewController
        historyView.isFirstTime = false
        historyView.arrayData = arrayDataDetails
        historyView.arrayRipetizioni = arrayRipetizioniDetails
        historyView.arrayPeso = arrayPesoDetails
        historyView.arrayRecupero = arrayRecuperoDetails
        historyView.tableView.reloadData()
    }
}

Answer 1

当您按下后退按钮时,导航控制器将调用,navigationController(willShowViewController:)以便您可以使用它将数据传递回初始视图控制器.一个例子如下所示:

使用UINavigationControllerDelegate:

class DetailsViewController: UIViewController, UINavigationControllerDelegate {
                                                        //     ^
    var data: [String] = []                             // Important!

    override func viewDidLoad() {
        super.viewDidLoad()

        navigationController?.delegate = self

        data = ["data has changed!"]
    }
}

斯威夫特2:

extension DetailsViewController: UINavigationControllerDelegate {
    func navigationController(navigationController: UINavigationController, willShowViewController viewController: UIViewController, animated: Bool) {
        if let controller = viewController as? ProgressTableViewController {
            controller.data = data    // Here you pass the data back to your original view controller
        }
    }
}

斯威夫特3:

extension DetailsViewController: UINavigationControllerDelegate {
    func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
        (viewController as? ProgressTableViewController)?.data = data // Here you pass the to your original view controller
    }
}

在这个例子中,键是使用UINavigationControllerDelegate和设置导航控制器的委托(在这种情况下是它self).完成此操作后,您可以使用后退按钮将数据发送回初始视图控制器.

就个人而言,我更喜欢为我的数据使用一个类:

为您的数据使用自定义类:

class Data {
    var array: [String] = []
}

进度视图控制器:

class ProgressTableViewController: UITableViewController {

    var data = Data()

    override func viewDidLoad() {
        super.viewDidLoad()

        data.array = ["some data"]
    }

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

        tableView.reloadData()
    }

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

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = UITableViewCell()

        cell.textLabel?.text = data.array[indexPath.row]

        return cell
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        performSegue(withIdentifier: "exerciseSegue", sender: self)
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "exerciseSegue" {
            let destination = segue.destinationViewController as! DetailsViewController
            destination.data = data
        }
    }
}

细节视图控制器:

class DetailsViewController: UIViewController {

    var data = Data()

    override func viewDidLoad() {
        super.viewDidLoad()

        data.array = ["data has changed!"]
    }
}

在最后一个示例中,您不必担心传递数据.每当您更改数据时,使用相同类的控制器也会进行更改.