如何从另一个控制器打开嵌入式 segue 控制器？

Question

我正在按照与此应用 https://github.com/Bailig/SurveyApp 相同的设计方法制作应用。

在上面的 GitHub 项目中，控制器的设计方式类似于带有 ContainerView 的普通 ViewController。而且这个普通的 ViewController 是 Embed Segue 与第一个控制器或第一页。所有后续屏幕的容器视图都将被替换。
在上面的项目中，最后有一个感谢页面，在我的应用程序中，我在感谢页面上放置了一个按钮。我想通过点击感谢页面中的按钮再次打开第一页。如何从最后一页控制器/FourthController 执行此操作？

视图控制器

class ViewController: UIViewController {

var currentController: UIViewController?
var pageIndex = 1
var survey = Survey()

@IBOutlet weak var backButton: UIButton!
@IBOutlet weak var nextButton: UIButton!
@IBOutlet weak var containerView: UIView!
@IBOutlet weak var progressLabel: UILabel!
@IBAction func nextTapped(_ sender: Any) {
    switch pageIndex {
    case 1:
        let nextController = storyboard?.instantiateViewController(withIdentifier: "SecondController")
        if let fromController = currentController, let toController = nextController as? SecondController {
            toController.survey = survey
            moveAndSizeChildControllers(fromController: fromController, toController: toController)
            pageIndex += 1
            setButtonAndProgressLabel()
        }
    case 2:
        let nextController = storyboard?.instantiateViewController(withIdentifier: "ThirdController")
        if let fromController = currentController, let toController = nextController as? ThirdController {
            toController.survey = survey
            moveAndSizeChildControllers(fromController: fromController, toController: toController)
            pageIndex += 1
            setButtonAndProgressLabel()
        }
    case 3:
        let nextController = storyboard?.instantiateViewController(withIdentifier: "FourthController")
        if let fromController = currentController, let toController = nextController as? FourthController {
            toController.survey = survey
            moveAndSizeChildControllers(fromController: fromController, toController: toController)
            pageIndex += 1
            setButtonAndProgressLabel()
        }
    default:
        break
    }
}
@IBAction func backTapped(_ sender: Any) {
    switch pageIndex {
    case 2:
        let nextController = storyboard?.instantiateViewController(withIdentifier: "FirstController")
        if let fromController = currentController, let toController = nextController as? FirstController {
            toController.survey = survey
            moveAndSizeChildControllers(fromController: fromController, toController: toController)
            pageIndex -= 1
            setButtonAndProgressLabel()
        }
    case 3:
        let nextController = storyboard?.instantiateViewController(withIdentifier: "SecondController")
        if let fromController = currentController, let toController = nextController as? SecondController {
            toController.survey = survey
            moveAndSizeChildControllers(fromController: fromController, toController: toController)
            pageIndex -= 1
            setButtonAndProgressLabel()
        }
    default:
        break
    }
}

@IBOutlet weak var backTapped: UIButton!

override func viewDidLoad() {
    super.viewDidLoad()

}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    currentController = segue.destination
    if let firstController = currentController as? FirstController {
        firstController.survey = survey
    }
    setButtonAndProgressLabel()
}

func moveAndSizeChildControllers(fromController: UIViewController, toController: UIViewController) {
    fromController.willMove(toParentViewController: nil)

    toController.view.frame = containerView.bounds

    addChildViewController(toController)
    containerView.addSubview(toController.view)

    // animatin
    toController.view.alpha = 0
    UIView.animate(withDuration: 0.5, animations: { 
        toController.view.alpha = 1
        fromController.view.alpha = 0 
    }) { (completed) in
        fromController.view.removeFromSuperview()
        fromController.removeFromParentViewController()

        toController.didMove(toParentViewController: self)
        self.currentController = toController
    }
}
}

Answer 1

您可以使用通知管理它

在 ViewController 中添加（主）

override func viewDidLoad() {
    super.viewDidLoad()

    NotificationCenter.default.addObserver(self, selector: #selector(navigateToFirstPage), name:NSNotification.Name(rawValue:"NavigateToFirstPage") , object: nil)
}

@objc private func navigateToFirstPage() {

    pageIndex = 2
    self.backTapped(UIButton())
}

添加你的第四个ViewController

// This is your button from where you need to perform action
@IBAction func thanksButtonAction(_ sender: Any) {

     NotificationCenter.default.post(name: NSNotification.Name(rawValue:"NavigateToFirstPage"), object: nil)
}

Answer 2

我最好使用delegation pattern。它易于管理且易于理解。

在FourthController 顶部导入后需要添加

protocol FourthControllerThankDelegate {
    func didTapYourButton()
}

然后在该类中添加变量

class FourthController: UIViewController {

    weak var delegate: FourthControllerThankDelegate?
    ...
}

那么您需要在按钮操作处理程序中调用 didTapYourButton()

@IBAction func thanksButtonTapped(_ sender: Any) {
    delegate?.didTapYourButton()
}

然后在 ViewController 函数中 nextTapped: 你需要将此视图控制器设置为 FourthController 的委托

case 3:
     ... // I have skipped code above 
     toController.delegate = self
     setButtonAndProgressLabel()
}

最后你需要处理委托操作

extension ViewController: FourthControllerThankDelegate {
    func didTapYoutButton {
        pageIndex = 2
        backTapped(self)
    }
}

当您这样做时，backTapped 处理程序会将您移动到第一页。这不是退后的最佳方式。为了改善这一点，您可以创建一个函数“displayMeFirstPage”并将部分逻辑从 backTapped() case: 2 移到那里，并在该案例和委托处理程序内部调用它。有很多方法可以改善导航。如果您有任何问题，请告诉我。