在水平流iOS 12中的TabbarCoordinator中未调用后退按钮

Question

协调器模式是一个古老的话题，许多图书馆都试图解决它，我正在简单的示例应用程序中学习它。我当前的设置是3个rootViewControlers：LoadingStateCoordinator，WelcomeCoordinator，TabBarCoordinator，但UIKit和协调器之间缺少连接。我正在尝试使用UINavigationController来实现它，但是没有调用该按钮。我需要一种方法来连接到后退按钮和一个可重用的协调器，可以将其按入并进行相应的分配（即没有RxSwift）。*将“欢迎”屏幕设置为父/主导航，并始终能够返回到它。 *因此，在用户从显示的模态视图（垂直流）中选择一种形式后，我将按下一个TabBarCoordinator（水平）。所有的viewControllers都为empty .storyboard，UIViewController和Coordinator都在TabBar之外。在这里，由于子选项卡协调器的设置，我只有一个协调器，而后退按钮的点击需要魔术。目前，仅当用户来自LoadingStateCoordinator时才调用此方法。我需要在那里将用户送回“欢迎”屏幕，以便他们可以更改入职设置。这是LoadingStateCoordinator的第一个代码：

final class LoadingStateCoordinator: NSObject, Coordinator {
    *// MARK: - Inputs required*

    var childCoordinators: [Coordinator]
    var presenter: UINavigationController
    private let window: UIWindow

    *// MARK: - Initialization*
    init(window: UIWindow) {
        self.window = window
        childCoordinators = []
        presenter = UINavigationController()
    }
    *// MARK: - Coordinator*
     func start() {
        let controller: LoadingStateViewController = LoadingStateViewController.instantiate()
        window.rootViewController = controller
        controller.delegate = self
        }

}
    *// MARK: - LoadingViewControllerDelegate*
extension LoadingStateCoordinator : LoadingViewControllerDelegate {
    func performScreenSwitch() {
        if UserDefaults.standard.userWasHere == false {
            let tabCoordinator: TabBarCoordinator = TabBarCoordinator(window: window, tabBarController: UITabBarController())
            window.rootViewController = presenter
            addChildCoordinator(tabCoordinator)
            tabCoordinator.start()
            presenter.pushViewController(tabCoordinator.tabBarController!, animated: true)

        } else {
            let welcomeCoordinator = WelcomeCoordinator(window: window, presenter: presenter)
            window.rootViewController = welcomeCoordinator.presenter
            addChildCoordinator(welcomeCoordinator)
            welcomeCoordinator.start()
        }
    }
}

这是TabBarCoordinator，需要执行回到Welcome屏幕的操作。当我显示popToRoot功能时，它会按“欢迎”屏幕，但所有按钮都没有显示。我想是保留周期的问题。我是否需要funadametally另一个设置？在此设置中是否可以使用popToRoot（vc）？我尝试的结果以运行时错误“弹出到不存在的控制器”结束。需要执行此操作的TabBarCoordinator代码：

final class TabBarCoordinator: NSObject, Coordinator {
    internal var presenter: UINavigationController
    internal var tabBarController: UITabBarController?
    internal var childCoordinators: [Coordinator]
    var parentCoordinator: LoadingStateCoordinator?
    lazy var leftBtn: UIBarButtonItem = {
        let button = UIButton(type: .system)
        button.setImage(UIImage(systemName: "arrow.turn.up.left"), for: .normal)
        button.sizeToFit()
        button.addTarget(self,
                         action: #selector(self.popToRoot(_:)),
                         for: .touchUpInside)
      return UIBarButtonItem(customView: button)
    }()

    init(window: UIWindow, tabBarController: UITabBarController) {
        self.tabBarController = tabBarController
        childCoordinators = []
        self.presenter = UINavigationController()

    }
     func start() {
        performGetTabBar()
        self.presenter.delegate = self
    }
    private func performGetTabBar() {
        let coordinators: [Coordinator] = generateTabCoordinators()

        coordinators.forEach({ coordinator in
            coordinator.start()
            addChildCoordinator(coordinator)
        })

        let presenters: [UIViewController] = coordinators.map({ coordinator -> UIViewController in
            return coordinator.presenter
        })
        leftBtn.style = .plain
        tabBarController?.navigationItem.leftBarButtonItem = leftBtn
        tabBarController?.setViewControllers(presenters, animated: false)
        selectTab(type: SurfTripCoordinator.self)
    }

    private func generateTabCoordinators() -> [Coordinator] {
        let calculatorCoordinator: CalculatorCoordinator = CalculatorCoordinator(presenter: UINavigationController())
        let tripCoordinator: SurfTripCoordinator = SurfTripCoordinator(presenter: UINavigationController())
        let sellCoordinator: SavedTripsCoordinator = SavedTripsCoordinator(presenter: UINavigationController())
        return [calculatorCoordinator, tripCoordinator, sellCoordinator]
    }
    *//this is not being called when coming from vertical flow*
    @objc func popToRoot(_ sender: UIBarButtonItem) {
        let storyboard: UIStoryboard = UIStoryboard(name: Constants.Storyboards.welcomeViewCoordinator, bundle: nil)
        let controller: WelcomeViewController = WelcomeViewController.instantiate(from: storyboard)
        tabBarController?.navigationController?.pushViewController(controller, animated: true)

    }
}

extension TabBarCoordinator: UINavigationControllerDelegate {

    func selectTab<T: Coordinator>(type _: T.Type) {
        guard let index = childCoordinators.firstIndex(where: { coordinator in
            coordinator is T
        }) else {
            return
        }
        tabBarController?.selectedIndex = index
  }
}

这是当前的WelcomeCoordinator设置

class WelcomeCoordinator: NSObject, Coordinator {
    internal var presenter: UINavigationController
    var childCoordinators: [Coordinator]

    init(window: UIWindow, presenter: UINavigationController) {
        self.presenter = presenter
        childCoordinators = []

    }
    func start() {
        let storyboard: UIStoryboard = UIStoryboard(name: Constants.Storyboards.welcomeViewCoordinator, bundle: nil)
        let controller: WelcomeViewController = WelcomeViewController.instantiate(from: storyboard)
        controller.delegate = self
        presenter.pushViewController(controller, animated: true)
    }
}

extension WelcomeCoordinator : WelcomeViewControllerDelegate {

    func performAddLevel() {
        let addLevelCoordinator: AddLevelViewCoordinator = AddLevelViewCoordinator(presenter: UINavigationController())
        addLevelCoordinator.start()
        addChildCoordinator(addLevelCoordinator)
        addLevelCoordinator.presenter.modalPresentationStyle = .fullScreen
        presenter.present(addLevelCoordinator.presenter, animated: true, completion: nil)
    }
}

很长的帖子，很抱歉，我希望有更多的本地方法可以做到这一点...

Answer 1

好，所以我找到了适用于我的情况的后退按钮解决方案：不使用pushViewController，因为它带有后退按钮。 presenter.setViewControllers([tabCoordinator.tabBarController!], animated: true)，然后将navBar设置为隐藏。我制作了自己的navItem按钮以导航到rootVC。现在尝试分配和删除所有子tabBar协调器。