如何在iOS上找到最顶层的视图控制器

Question

如何在iOS上找到最顶层的视图控制器

iosobjective-cuiviewuiviewcontrolleruikit

285

我遇到了几种情况，需要找到“最上层”的视图控制器（负责当前视图的视图控制器），但没有找到方法。

基本上，这个挑战是这样的：假设一个类不是视图控制器（或视图）[并且没有活动视图的地址]，也没有传入最上面视图控制器的地址（或者比如导航控制器的地址），那么是否可能找到该视图控制器呢？（如果可以，怎么实现？）

或者，如果找不到它，是否可能找到最上层的视图？

- Hot Licks

那么你的意思是说这是不可能的。 - Hot Licks

@Daniel 不，我的意思是你的代码似乎需要重新设计，因为你很少需要知道这个。此外，“最顶层”的概念只在特定情况下有效，即使在那种情况下也不总是有效。 - Dave DeLong

@Daniel，我误读了您的问题。尝试回答此问题时有很多情况需要考虑。这取决于您的视图控制器流程。 @Wilbur的答案应该是追踪它的好起点。 - Deepak Danduprolu

4

@Daniel：添加第二个UIWindow 对于警报视图类似的覆盖效果很有效。 - Wilbur Vandrsmith

是的，UIWindow似乎是实现警报的方法。这并不能解决找出最上层视图控制器（想要将其放在顶部的位置）的另一个问题，但我想这些问题需要分别处理。 - Hot Licks

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42个回答

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- JonasG · Answer 1

这是对Eric答案的改进：

UIViewController *_topMostController(UIViewController *cont) {
    UIViewController *topController = cont;

    while (topController.presentedViewController) {
        topController = topController.presentedViewController;
    }

    if ([topController isKindOfClass:[UINavigationController class]]) {
        UIViewController *visible = ((UINavigationController *)topController).visibleViewController;
        if (visible) {
            topController = visible;
        }
    }

    return (topController != cont ? topController : nil);
}

UIViewController *topMostController() {
    UIViewController *topController = [UIApplication sharedApplication].keyWindow.rootViewController;

    UIViewController *next = nil;

    while ((next = _topMostController(topController)) != nil) {
        topController = next;
    }

    return topController;
}

_topMostController(UIViewController *cont)是一个帮助函数。

现在你只需要调用topMostController()函数，便可以返回最顶层的UIViewController！

- FishStix · Answer 2

@implementation UIWindow (扩展)
- (UIViewController*) topMostController
{
    // 获取顶层控制器
    UIViewController *topController = [self rootViewController];
while (topController.presentedViewController) {
        topController = topController.presentedViewController;
    }
return topController;
}
@end

- Kamran Khan · Answer 3

这是我的观点。感谢@Stakenborg指出了跳过获取UIAlertView作为最顶层控制器的方法。

-(UIWindow *) returnWindowWithWindowLevelNormal
{
    NSArray *windows = [UIApplication sharedApplication].windows;
    for(UIWindow *topWindow in windows)
    {
        if (topWindow.windowLevel == UIWindowLevelNormal)
            return topWindow;
    }
    return [UIApplication sharedApplication].keyWindow;
}

-(UIViewController *) getTopMostController
{
    UIWindow *topWindow = [UIApplication sharedApplication].keyWindow;
    if (topWindow.windowLevel != UIWindowLevelNormal)
    {
        topWindow = [self returnWindowWithWindowLevelNormal];
    }

    UIViewController *topController = topWindow.rootViewController;
    if(topController == nil)
    {
        topWindow = [UIApplication sharedApplication].delegate.window;
        if (topWindow.windowLevel != UIWindowLevelNormal)
        {
            topWindow = [self returnWindowWithWindowLevelNormal];
        }
        topController = topWindow.rootViewController;
    }

    while(topController.presentedViewController)
    {
        topController = topController.presentedViewController;
    }

    if([topController isKindOfClass:[UINavigationController class]])
    {
        UINavigationController *nav = (UINavigationController*)topController;
        topController = [nav.viewControllers lastObject];

        while(topController.presentedViewController)
        {
            topController = topController.presentedViewController;
        }
    }

    return topController;
}

- Bartłomiej Semańczyk · Answer 4

这是一个关于UIApplication的简单扩展，用Swift编写。

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
    }
}

简单用法：

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

- lifuqing_ios · Answer 5

- (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;
    }
}

- Saranjith · Answer 6

Swift 4.2 扩展

extension UIApplication {

    class func topViewController(controller: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
        if let navigationController = controller as? UINavigationController {
            return topViewController(controller: navigationController.visibleViewController)
        }
        if let tabController = controller as? UITabBarController {
            if let selected = tabController.selectedViewController {
                return topViewController(controller: selected)
            }
        }
        if let presented = controller?.presentedViewController {


            return topViewController(controller: presented)
        }
        return controller
    }
}

可以从任何地方使用它，例如：

 UIApplication.topViewController()?.present(yourController, animated: true, completion: nil)

或者像这样：

 UIApplication.topViewController()?
                    .navigationController?
                    .popToViewController(yourController,
                                         animated: true)

适用于任何类似于UINavigationController、UITabBarController的类

享受吧！

- nalexn · Answer 7

以下是Swift 4.2 中简洁而全面的解决方案，考虑了 UINavigationControllers、UITabBarControllers、presented 和 child 视图控制器：

extension UIViewController {
  func topmostViewController() -> UIViewController {
    if let navigationVC = self as? UINavigationController,
      let topVC = navigationVC.topViewController {
      return topVC.topmostViewController()
    }
    if let tabBarVC = self as? UITabBarController,
      let selectedVC = tabBarVC.selectedViewController {
      return selectedVC.topmostViewController()
    }
    if let presentedVC = presentedViewController {
      return presentedVC.topmostViewController()
    }
    if let childVC = children.last {
      return childVC.topmostViewController()
    }
    return self
  }
}

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

使用方法：

let viewController = UIApplication.shared.topmostViewController()

- Martin Algesten · Answer 8

另一种Swift解决方案

func topController() -> UIViewController? {

    // recursive follow
    func follow(from:UIViewController?) -> UIViewController? {
        if let to = (from as? UITabBarController)?.selectedViewController {
            return follow(to)
        } else if let to = (from as? UINavigationController)?.visibleViewController {
            return follow(to)
        } else if let to = from?.presentedViewController {
            return follow(to)
        }
        return from
    }

    let root = UIApplication.sharedApplication().keyWindow?.rootViewController

    return follow(root)

}

- Esqarrouth · Answer 9

另一种Swift解决方案:

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

    return topController!
}

- Tom Andersen · Answer 10

以下是我成功尝试的方法。

我发现有时候控制器在关键窗口上是空的，因为关键窗口是一些类似于警告等操作系统的东西。

 + (UIViewController*)topMostController
 {
     UIWindow *topWndow = [UIApplication sharedApplication].keyWindow;
     UIViewController *topController = topWndow.rootViewController;

     if (topController == nil)
     {
         // The windows in the array are ordered from back to front by window level; thus,
         // the last window in the array is on top of all other app windows.
         for (UIWindow *aWndow in [[UIApplication sharedApplication].windows reverseObjectEnumerator])
         {
             topController = aWndow.rootViewController;
             if (topController)
                 break;
         }
     }

     while (topController.presentedViewController) {
         topController = topController.presentedViewController;
     }

     return topController;
 }