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

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
}

其他回答

斯威夫特 5+

声明

func topViewController() -> 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
        
    }
    
}

Use

topViewController()?.view.addSubview(UIView())

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
}

基于上面的Bob -c:

斯威夫特3.0

extension UIWindow {


    func visibleViewController() -> UIViewController? {
        if let rootViewController: UIViewController  = self.rootViewController {
            return UIWindow.getVisibleViewControllerFrom(vc: rootViewController)
        }
        return nil
    }

    class func getVisibleViewControllerFrom(vc:UIViewController) -> UIViewController {

        if vc.isKind(of: UINavigationController.self) {

            let navigationController = vc as! UINavigationController
            return UIWindow.getVisibleViewControllerFrom( vc: navigationController.visibleViewController!)

        } else if vc.isKind(of: UITabBarController.self) {

            let tabBarController = vc as! UITabBarController
            return UIWindow.getVisibleViewControllerFrom(vc: tabBarController.selectedViewController!)

        } else {

            if let presentedViewController = vc.presentedViewController {

                return UIWindow.getVisibleViewControllerFrom(vc: presentedViewController)

            } else {

                return vc;
            }
        }
    }
}

对我来说,最好的解决方案是一个带有函数的扩展。 用这个扩展名创建一个swift文件

首先是UIWindow扩展:

public extension UIWindow {
    var visibleViewController: UIViewController? {
        return UIWindow.visibleVC(vc: self.rootViewController)
    }

    static func visibleVC(vc: UIViewController?) -> UIViewController? {
        if let navigationViewController = vc as? UINavigationController {
            return UIWindow.visibleVC(vc: navigationViewController.visibleViewController)
        } else if let tabBarVC = vc as? UITabBarController {
            return UIWindow.visibleVC(vc: tabBarVC.selectedViewController)
        } else {
            if let presentedVC = vc?.presentedViewController {
                return UIWindow.visibleVC(vc: presentedVC)
            } else {
                return vc
            }
        }
    }
}

在该文件中添加函数

func visibleViewController() -> UIViewController? {
    let appDelegate = UIApplication.shared.delegate
    if let window = appDelegate!.window {
        return window?.visibleViewController
    }
    return nil
}

如果你想使用它,你可以在任何地方调用它。 例子:

  override func viewDidLoad() {
    super.viewDidLoad()
      if let topVC = visibleViewController() {
             //show some label or text field 
    }
}

文件代码如下:

import UIKit

public extension UIWindow {
    var visibleViewController: UIViewController? {
        return UIWindow.visibleVC(vc: self.rootViewController)
    }

    static func visibleVC(vc: UIViewController?) -> UIViewController? {
        if let navigationViewController = vc as? UINavigationController {
            return UIWindow.visibleVC(vc: navigationViewController.visibleViewController)
        } else if let tabBarVC = vc as? UITabBarController {
            return UIWindow.visibleVC(vc: tabBarVC.selectedViewController)
        } else {
            if let presentedVC = vc?.presentedViewController {
                return UIWindow.visibleVC(vc: presentedVC)
            } else {
                return vc
            }
        }
    }
}

func visibleViewController() -> UIViewController? {
    let appDelegate = UIApplication.shared.delegate
    if let window = appDelegate!.window {
        return window?.visibleViewController
    }
    return nil
}

在一个非常罕见的情况下,使用自定义segue,最顶层的视图控制器不在导航堆栈或选项卡栏控制器中或被呈现,但它的视图被插入到关键窗口子视图的顶部。

在这种情况下,有必要检查UIApplication.shared.keyWindow.subviews.last == self。视图来确定当前视图控制器是否是最顶端的。