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
var topViewController: UIViewController? {
guard var topViewController = UIApplication.shared.keyWindow?.rootViewController else { return nil }
while let presentedViewController = topViewController.presentedViewController {
topViewController = presentedViewController
}
return topViewController
}
其他回答
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。
我使用下面的代码来获得topViewController-
它向后兼容旧的iOS版本，并照顾UIScene太
extension UIApplication {
func topViewController() -> UIViewController? {
var topViewController: UIViewController? = nil
if #available(iOS 13, *) {
for scene in connectedScenes {
if let windowScene = scene as? UIWindowScene {
for window in windowScene.windows {
if window.isKeyWindow {
topViewController = window.rootViewController
}
}
}
}
} else {
topViewController = keyWindow?.rootViewController
}
while true {
if let presented = topViewController?.presentedViewController {
topViewController = presented
} else if let navController = topViewController as? UINavigationController {
topViewController = navController.topViewController
} else if let tabBarController = topViewController as? UITabBarController {
topViewController = tabBarController.selectedViewController
} else {
// Handle any other third party container in `else if` if required
break
}
}
return topViewController
}
}
它可以这样使用:
let topController = UIApplication.shared.topViewController()
topController?.present(controllerToPresent, animated: true, completion: nil)
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
}
在Swift 3中找到可见的viewController
if let viewControllers = window?.rootViewController?.childViewControllers {
let prefs = UserDefaults.standard
if viewControllers[viewControllers.count - 1] is ABCController{
print("[ABCController] is visible")
}
}
这段代码找到最后添加的或最后可见的活动控制器。
我已经在AppDelegate中使用它来查找活动视图控制器
var topViewController: UIViewController? {
guard var topViewController = UIApplication.shared.keyWindow?.rootViewController else { return nil }
while let presentedViewController = topViewController.presentedViewController {
topViewController = presentedViewController
}
return topViewController
}
