ios - 调用rootViewController后，NavigationController不显示

我对Swift比较陌生
尝试使用窥视和弹出PreviewActionItems“ edit”在编辑模式下打开SpeciesDetailViewController。尝试获取提示以显示SpeciesDetailViewController时出现问题，并收到错误消息"Warning: Attempt to present SpeciesDetailViewController whose view is not in the window hierarchy"。我在found here上实现了Jacob Davis的解决方案。

这解决了窗口层次结构错误，但是，在调用SpeciesDetailViewController控制器时，导航控制器和tabBarController均未显示。



虽然我认为这是由SpeciesDetailViewController称为top viewController引起的，但我对如何解决此问题感到困惑。

您能帮我同时显示导航控制器和tabBarController吗？

以下是我当前的代码：

主视图控制器

func showDetailsViewController() {

    let topVC = topMostController()
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let vc = storyboard.instantiateViewController(withIdentifier: "SpeciesDetailViewController") as! SpeciesDetailViewController
    topVC.present(vc, animated: true, completion: nil)

}

func topMostController() -> UIViewController {
    var topController: UIViewController = UIApplication.shared.keyWindow!.rootViewController!
    while (topController.presentedViewController != nil) {
        topController = topController.presentedViewController!
    }

    return topController
}

最佳答案

对于UITabBarController和UINavigationController，您需要不同的实现。

这是我用来获取topMostViewController的代码：

protocol TopUIViewController {
    func topUIViewController() -> UIViewController?
}

extension UIWindow : TopUIViewController {
    func topUIViewController() -> UIViewController? {
        if let rootViewController = self.rootViewController {
            return self.recursiveTopUIViewController(from: rootViewController)
        }

        return nil
    }

    private func recursiveTopUIViewController(from: UIViewController?) -> UIViewController? {
        if let topVC = from?.topUIViewController() { return recursiveTopUIViewController(from: topVC) ?? from }
        return from
    }
}

extension UIViewController : TopUIViewController {
    @objc open func topUIViewController() -> UIViewController? {
        return self.presentedViewController
    }
}

extension UINavigationController {
    override open func topUIViewController() -> UIViewController? {
        return self.visibleViewController
    }
}

extension UITabBarController {
    override open func topUIViewController() -> UIViewController? {
        return self.selectedViewController ?? presentedViewController
    }
}

现在，您可以使用它从您的应用程序中获取topUIViewController，而与您拥有的UIViewController堆栈无关，包括UINavigationController，UITabBarViewController。

let topVC = UIApplication.shared.keyWindow!.rootViewController!.topUIViewController()