使用这段代码找到top most UIViewController

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

对于任何寻求快速5/iOS 13+解决方案的人(keywindow自iOS 13以来已弃用)

extension UIApplication {

    class func getTopMostViewController() -> UIViewController? {
        let keyWindow = UIApplication.shared.windows.filter {$0.isKeyWindow}.first
        if var topController = keyWindow?.rootViewController {
            while let presentedViewController = topController.presentedViewController {
                topController = presentedViewController
            }
            return topController
        } else {
            return nil
        }
    }
}

你把密码放哪了?

我在我的演示中尝试了你的代码，我发现，如果你把代码放进去

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool { 

将失败，因为关键窗口已经设置。

但我把你的代码放到了视图控制器中

override func viewDidLoad() {

它就是有用。

presentViewController显示一个视图控制器。它不会返回一个视图控制器。如果你不使用UINavigationController，你可能正在寻找presenttedviewcontroller，你需要从根开始，向下迭代所呈现的视图。

if var topController = UIApplication.sharedApplication().keyWindow?.rootViewController {
    while let presentedViewController = topController.presentedViewController {
        topController = presentedViewController
    }

    // topController should now be your topmost view controller
}

对于Swift 3+:

if var topController = UIApplication.shared.keyWindow?.rootViewController {
    while let presentedViewController = topController.presentedViewController {
        topController = presentedViewController
    }

    // topController should now be your topmost view controller
}

适用于iOS 13+

let keyWindow = UIApplication.shared.windows.filter {$0.isKeyWindow}.first

if var topController = keyWindow?.rootViewController {
    while let presentedViewController = topController.presentedViewController {
        topController = presentedViewController
    }

// topController should now be your topmost view controller
}

import UIKit

extension UIApplication {

    // MARK: Choose keyWindow as per your choice
    var currentWindow: UIWindow? {
        connectedScenes
        .filter({$0.activationState == .foregroundActive})
        .map({$0 as? UIWindowScene})
        .compactMap({$0})
        .first?.windows
        .filter({$0.isKeyWindow}).first
    }

    // MARK: Choose keyWindow as per your choice
    var keyWindow: UIWindow? {
        UIApplication.shared.windows.first { $0.isKeyWindow }
    }

    class func topMostViewController(base: UIViewController? = UIApplication.shared.currentWindow?.rootViewController) -> UIViewController? {

        if let nav = base as? UINavigationController {
            return topMostViewController(base: nav.visibleViewController)
        }

        if let tab = base as? UITabBarController {
            let moreNavigationController = tab.moreNavigationController

            if let top = moreNavigationController.topViewController, top.view.window != nil {
                return topMostViewController(base: top)
            } else if let selected = tab.selectedViewController {
                return topMostViewController(base: selected)
            }
        }
        if let presented = base?.presentedViewController {
            return topMostViewController(base: presented)
        }
        return base
    }
}

https://gist.github.com/db0company/369bfa43cb84b145dfd8 我对这个网站上的答案和评论做了一些测试。对我来说，以下方法有效

extension UIViewController {
    func topMostViewController() -> UIViewController {

        if let presented = self.presentedViewController {
            return presented.topMostViewController()
        }

        if let navigation = self as? UINavigationController {
            return navigation.visibleViewController?.topMostViewController() ?? navigation
        }

        if let tab = self as? UITabBarController {
            return tab.selectedViewController?.topMostViewController() ?? tab
    }

        return self
    }
}

extension UIApplication {
    func topMostViewController() -> UIViewController? {
        return self.keyWindow?.rootViewController?.topMostViewController()
    }
}

然后，通过以下方法获取top viewController:

UIApplication.shared.topMostViewController()