childViewController在containerView中的失真度及对提出的containerView的返回

Question

在取消容器视图中的childviewController显示的模态视图时，我遇到了一些问题。我有一个UINavigationController as rootViewController (MainNavigationController)，并呈现了一个来自selectedSegmentIndex 1 (secondViewController)的childViewControllers的模态。该模型显示得很好，但当我拒绝将该模型返回到secondViewController(HomeController的一个子类)时，它会将我返回到selectedIndex 0，而不是从selectedIndex 1 childViewController返回。我希望这个模式能够拒绝用户并将其返回给childViewController，它是从( secondViewController)中呈现的，而不是返回到selectedIndex 0。提前感谢！

// NavigationConroller作为rootViewController

class MainNavigationController: UINavigationController {

    var segmentedController: UISegmentedControl!

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

        let vc1 = TravelersFeedVC()
        let vc2 = ProfileVC()

        if isLoggedIn() {
            // assume user is logged in
            let homeController = HomeController()
            viewControllers = [homeController]
            homeController.firstViewController = vc1
            homeController.secondViewController = vc2

        } else {
            perform(#selector(showLoginController), with: nil, afterDelay: 0.01)
        }
    }

    fileprivate func isLoggedIn() ->  Bool {
        return UserDefaults.standard.isLoggedIn()
    }

    func showLoginController() {
        let loginController = LoginController()
        present(loginController, animated: true, completion: {
            // perhaps do something here later
        })
    }
}

// HomeController作为parentViewController

class HomeController: UIViewController, FBSDKLoginButtonDelegate {

    // child view controllers to put inside content view
    var firstViewController: TravelersFeedVC?
    var secondViewController: ProfileVC?

    private var activeViewController: UIViewController? {
        didSet {
            removeInactiveViewController(inactiveViewController: oldValue)
            updateActiveViewController()
        }
    }

    private func removeInactiveViewController(inactiveViewController: UIViewController?) {
        if let inActiveVC = inactiveViewController {
            // call before removing child view controller's view from hierarchy
            inActiveVC.willMove(toParentViewController: nil)

            inActiveVC.view.removeFromSuperview()

            // call after removing child view controller's view from hierarchy
            inActiveVC.removeFromParentViewController()
        }
    }

    private func updateActiveViewController() {
        if let activeVC = activeViewController {
            // call before adding child view controller's view as subview
            addChildViewController(activeVC)

            activeVC.view.frame = contentView.bounds
            contentView.addSubview(activeVC.view)

            // call before adding child view controller's view as subview
            activeVC.didMove(toParentViewController: self)
        }
    }

    // UI elements
    lazy var contentView: UIView = {
        let tv = UIView()
        tv.backgroundColor = UIColor.purple
        tv.translatesAutoresizingMaskIntoConstraints = false
        tv.layer.masksToBounds = true
        return tv
    }()


    var segmentedController: UISegmentedControl!

    override func viewDidLoad() {
        super.viewDidLoad()

        activeViewController = firstViewController

        checkIfUserIsLoggedIn()

        view.addSubview(contentView)

        setupProfileScreen()

        let items = ["Travelers", "Me"]
        segmentedController = UISegmentedControl(items: items)
        navigationItem.titleView = segmentedController

        segmentedController.tintColor = UIColor.black
        segmentedController.selectedSegmentIndex = 0

        // Add function to handle Value Changed events
        segmentedController.addTarget(self, action: #selector(HomeController.segmentedValueChanged(_:)), for: .valueChanged)

        navigationItem.leftBarButtonItem = UIBarButtonItem(title: "Sign Out", style: .plain, target: self, action: #selector(handleSignOut))
        navigationItem.leftBarButtonItem?.tintColor = UIColor.black

    }


    // reference to collectionViewController
    var travelersFeedVC: TravelersFeedVC!

    func segmentedValueChanged(_ sender:UISegmentedControl!)
    {
        switch segmentedController.selectedSegmentIndex {
        case 0:
            activeViewController = firstViewController

        case 1:
            activeViewController = secondViewController

        default: // Do nothing
            break
        }
    }

// secondViewcontroller在containerView中，其中的模态是从

class ProfileVC: UIViewController {

// button to present modal
    lazy var placesButton: UIButton = {
        let customButton = UIButton(type: .system)
        customButton.backgroundColor = UIColor.clear
//        customButton.frame = CGRect(x: 150, y: 50, width: 120, height: self.view.frame.height)
        customButton.setTitle("## of Places", for: .normal)
        customButton.titleLabel?.font = UIFont.boldSystemFont(ofSize: 16)
        customButton.setTitleColor(.white, for: .normal)
        customButton.addTarget(self, action: #selector(handleShowPlacesVC), for: .touchUpInside)

        return customButton
    }()

// function to call to present modal
    func handleShowPlacesVC() {
        let placesVC = PlacesTableVC()
        let navigationController = UINavigationController(rootViewController: placesVC)
        present(navigationController, animated: true, completion: nil)
    }

//情态观点驳回

   override func viewDidLoad() {
        super.viewDidLoad()

        navigationItem.leftBarButtonItem = UIBarButtonItem(title: "back", style: .plain, target: self, action: #selector(handleCancel))

    }

// dismiss modal view to return to secondViewController in childViewController containerView
    func handleCancel() {
        dismiss(animated: true, completion: nil)
    }

Answer 1

当关闭模态对话框时，将调用MainNavigationController中的MainNavigationController函数。在这里，您设置了一个新的homeController，它是childs。这将在设置为viewDidload的HomeController中触发firstViewController。尝试在那里设置一个断点，你就会看到它。

为了避免在viewDidAppear中创建内容，我建议使用viewDidLoad。

另一个提示：“解散”定义为：“取消视图控制器所呈现的视图控制器。”--例如，如果在您的模式vc之上打开警报，它将关闭警报，而不是模式视图(self)。一个正确的实现必须调用呈现控制器(打开它的控制器)："presentingViewController?.dismiss()“它在您的代码中工作，因为苹果已经实现了一个退步，因为没有任何显示，但它是一个陷阱，有时会引起一些麻烦。

Answer 2

虽然您是从子视图控制器调用present，但它实际上并不处理演示文稿。来自苹果文档

调用此方法的对象可能并不总是处理表示的对象。每种表示风格都有不同的规则来规范其行为。例如，全屏演示必须由本身覆盖整个屏幕的视图控制器进行。如果当前视图控制器无法完成请求，则会将请求转发到视图控制器层次结构的最接近的父节点，后者可以处理或转发请求。

由于要保持活动视图控制器的引用，一种解决方案可能是在解雇时显式设置索引。