代表返回 nil 并且没有被调用

Question

当单击button 时，我想要删除一个覆盖层，从而关闭ViewController。我已经调试过了，delegate 目前返回零。我不确定我在这里做错了什么。我错过了实施其他的东西吗？我什至尝试过打印语句，但什么都看不到。

protocol DismissOverlayDelegate: class {
    func dismissOverlay(_ sender: PlayersViewController)
}

class PlayersViewController: UIViewController {

    weak var delegate: DismissOverlayDelegate?

    @IBAction func getStartedTapped(_ sender: UIButton) {
        self.delegate?.dismissOverlay(self)
    }
}

在我的ViewController 中实现delegate 方法

class HomeViewController: UIViewController, DismissOverlayDelegate {

    @IBOutlet weak var customOverlay: CustomOverlayView!

    let playersViewController = PlayersViewController()

    override func viewDidLoad() {
        super.viewDidLoad()
        self.playersViewController.delegate = self
    }

    func dismissOverlay(_ sender: PlayersViewController) {
        self.customOverlay.removeFromView()
    }
}

delegate = (DismissOverlayDelegate?) nil

PlayersViewController 嵌入到 UIPageViewController 中

class HomeViewController: UIPageViewController, UIPageViewControllerDataSource {

    var pages = [UIViewController]()

    override func viewDidLoad() {
        super.viewDidLoad()
        for storyboardIDs in ["playersVC1","playersVC2"] {
            let viewController = self.storyboard?.instantiateViewController(withIdentifier: storyboardIDs)
            self.pages.append(viewController!)
        }
        self.dataSource = self
        self.setViewControllers([self.pages.first!], direction: .forward, animated: true)
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
        let currentIndex = self.pages.firstIndex(of: viewController)!
        if currentIndex > 0 {
            return self.pages[currentIndex - 1]
        }
        return nil
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        let currentIndex = self.pages.firstIndex(of: viewController)!
        if currentIndex < (self.pages.count - 1) {
            return self.pages[currentIndex + 1]
        }
        return nil
    }
}

Answer 1

如果您正在使用或想要使用委托进行调用或实现一些有根的东西，让我向您解释一下，您必须以正确的方式做到这一点。你做得很好没问题，但是委托的实现不正确，你的方法不能接受，所以试试这个：-

您的主视图控制器

class HomeViewController: UIViewController, DismissOverlayDelegate {

    @IBOutlet weak var customOverlay: UIView!

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    func dismissOverlay(_ sender: PlayersViewController) {
        self.customOverlay.removeFromSuperview()
    }

    @IBAction func go(_ sender: UIButton) {
        let vc = self.storyboard?.instantiateViewController(withIdentifier: "PlayersViewController") as! PlayersViewController
        vc.delegate = self
        self.navigationController?.pushViewController(vc, animated: true);
    }
}

这是你的游乐场 VC

protocol DismissOverlayDelegate: class {
    func dismissOverlay(_ sender: PlayersViewController)
}

class PlayersViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    weak var delegate: DismissOverlayDelegate?

    @IBAction func getStartedTapped(_ sender: UIButton) {
        self.delegate?.dismissOverlay(self)
    }

}

现在希望你明白你必须做什么......！

Answer 2

看来 PlayersViewController() 是错误的。 使用 StoryBoard 时应使用 instantiateInitialViewController() 或 instantiateInitialViewController()。

https://developer.apple.com/documentation/uikit/uistoryboard/1616214-instantiateviewcontroller

https://developer.apple.com/documentation/uikit/uistoryboard/1616213-instantiateinitialviewcontroller