这个解决方案是最完整的。它考虑到: UINavigationController UIPageViewController UITabBarController 最上面的视图控制器来自顶部视图控制器

以Swift 3为例。

有3个重载

//Get the topmost view controller for the current application.
public func MGGetTopMostViewController() -> UIViewController?  {

    if let currentWindow:UIWindow = UIApplication.shared.keyWindow {
        return MGGetTopMostViewController(fromWindow: currentWindow)
    }

    return nil
}

//Gets the topmost view controller from a specific window.
public func MGGetTopMostViewController(fromWindow window:UIWindow) -> UIViewController? {

    if let rootViewController:UIViewController = window.rootViewController
    {
        return MGGetTopMostViewController(fromViewController:  rootViewController)
    }

    return nil
}


//Gets the topmost view controller starting from a specific UIViewController
//Pass the rootViewController into this to get the apps top most view controller
public func MGGetTopMostViewController(fromViewController viewController:UIViewController) -> UIViewController {

    //UINavigationController
    if let navigationViewController:UINavigationController = viewController as? UINavigationController {
        let viewControllers:[UIViewController] = navigationViewController.viewControllers
        if navigationViewController.viewControllers.count >= 1 {
            return MGGetTopMostViewController(fromViewController: viewControllers[viewControllers.count - 1])
        }
    }

    //UIPageViewController
    if let pageViewController:UIPageViewController = viewController as? UIPageViewController {
        if let viewControllers:[UIViewController] = pageViewController.viewControllers {
            if viewControllers.count >= 1 {
                return MGGetTopMostViewController(fromViewController: viewControllers[0])
            }
        }
    }

    //UITabViewController
    if let tabBarController:UITabBarController = viewController as? UITabBarController {
        if let selectedViewController:UIViewController = tabBarController.selectedViewController {
            return MGGetTopMostViewController(fromViewController: selectedViewController)
        }
    }

    //Lastly, Attempt to get the topmost presented view controller
    var presentedViewController:UIViewController! = viewController.presentedViewController
    var nextPresentedViewController:UIViewController! = presentedViewController?.presentedViewController

    //If there is a presented view controller, get the top most prensentedViewController and return it.
    if presentedViewController != nil {
        while nextPresentedViewController != nil {

            //Set the presented view controller as the next one.
            presentedViewController = nextPresentedViewController

            //Attempt to get the next presented view controller
            nextPresentedViewController = presentedViewController.presentedViewController
        }
        return presentedViewController
    }

    //If there is no topmost presented view controller, return the view controller itself.
    return viewController
}

一个完整的非递归版本，照顾到不同的场景:

视图控制器正在呈现另一个视图 视图控制器是一个UINavigationController 视图控制器是一个UITabBarController

objective - c

 UIViewController *topViewController = self.window.rootViewController;
 while (true)
 {
     if (topViewController.presentedViewController) {
         topViewController = topViewController.presentedViewController;
     } else if ([topViewController isKindOfClass:[UINavigationController class]]) {
         UINavigationController *nav = (UINavigationController *)topViewController;
         topViewController = nav.topViewController;
     } else if ([topViewController isKindOfClass:[UITabBarController class]]) {
         UITabBarController *tab = (UITabBarController *)topViewController;
         topViewController = tab.selectedViewController;
     } else {
         break;
     }
 }

斯威夫特 4+

extension UIWindow {
    func topViewController() -> UIViewController? {
        var top = self.rootViewController
        while true {
            if let presented = top?.presentedViewController {
                top = presented
            } else if let nav = top as? UINavigationController {
                top = nav.visibleViewController
            } else if let tab = top as? UITabBarController {
                top = tab.selectedViewController
            } else {
                break
            }
        }
        return top
    }
}

I am thinking that perhaps one thing is being overlooked here. Perhaps it is better to pass the parent viewController into the function that is using the viewController. If you are fishing around in the view hierarchy to find the top view controller that it is probably violating separation of the Model layer and UI layer and is a code smell. Just pointing this out, I did the same, then realized it was much simpler just to pass it in to function, by having the model operation return to the UI layer where I have a reference to the view controller.

为了完成JonasG的回答(谁在遍历时遗漏了标签栏控制器)，这里是我返回当前可见的视图控制器的版本:

- (UIViewController*)topViewController {
    return [self topViewControllerWithRootViewController:[UIApplication sharedApplication].keyWindow.rootViewController];
}

- (UIViewController*)topViewControllerWithRootViewController:(UIViewController*)rootViewController {
    if ([rootViewController isKindOfClass:[UITabBarController class]]) {
        UITabBarController* tabBarController = (UITabBarController*)rootViewController;
        return [self topViewControllerWithRootViewController:tabBarController.selectedViewController];
    } else if ([rootViewController isKindOfClass:[UINavigationController class]]) {
        UINavigationController* navigationController = (UINavigationController*)rootViewController;
        return [self topViewControllerWithRootViewController:navigationController.visibleViewController];
    } else if (rootViewController.presentedViewController) {
        UIViewController* presentedViewController = rootViewController.presentedViewController;
        return [self topViewControllerWithRootViewController:presentedViewController];
    } else {
        return rootViewController;
    }
}

斯威夫特5

试试这个

let topVisibleVC = UIApplication.shared.keyWindow?.rootViewController?.visibleViewController

简单的扩展UIApplication在Swift:

注意:

它关心UITabBarController中的moreNavigationController

extension UIApplication {

    class func topViewController(baseViewController: UIViewController? = UIApplication.sharedApplication().keyWindow?.rootViewController) -> UIViewController? {

        if let navigationController = baseViewController as? UINavigationController {
            return topViewController(navigationController.visibleViewController)
        }

        if let tabBarViewController = baseViewController as? UITabBarController {

            let moreNavigationController = tabBarViewController.moreNavigationController

            if let topViewController = moreNavigationController.topViewController where topViewController.view.window != nil {
                return topViewController(topViewController)
            } else if let selectedViewController = tabBarViewController.selectedViewController {
                return topViewController(selectedViewController)
            }
        }

        if let splitViewController = baseViewController as? UISplitViewController where splitViewController.viewControllers.count == 1 {
            return topViewController(splitViewController.viewControllers[0])
        }

        if let presentedViewController = baseViewController?.presentedViewController {
            return topViewController(presentedViewController)
        }

        return baseViewController
    }
}

简单的用法:

if let topViewController = UIApplication.topViewController() {
    //do sth with top view controller
}