如果没有UINavigationController,我似乎无法得到最顶端的UIViewController。以下是我目前所掌握的:

UIApplication.sharedApplication().keyWindow?.rootViewController?.presentViewController(vc, animated: true, completion: nil)

然而,它似乎没有做任何事情。keyWindow和rootViewController似乎也不是nil值,所以可选的链接应该不是问题。

注意:这样做不是一个好主意。它打破了MVC模式。


当前回答

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
        }
    }
}

其他回答

我喜欢@dianz的回答,下面是swift 3的版本。它基本上是一样的,但他少了一个大括号,一些语法/变量/方法名已经改变了。所以它就在这里!

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

用法仍然是一样的:

if let topController = UIApplication.topViewController() {
    print("The view controller you're looking at is: \(topController)")
}

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。

你可以在AppDelegate中定义一个UIViewController变量,并在每个viewWillAppear中设置这个变量为self。(然而,dianz的答案是最好的答案。)

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)
    let appDel = UIApplication.sharedApplication().delegate as! AppDelegate
    appDel.currentVC = self
}

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
}
  var topViewController: UIViewController? {
        guard var topViewController = UIApplication.shared.keyWindow?.rootViewController else { return nil }
        while let presentedViewController = topViewController.presentedViewController {
            topViewController = presentedViewController
        }
        return topViewController
    }