我遇到了一些情况,现在,它将是方便的,能够找到“最顶层”的视图控制器(一个负责当前视图),但还没有找到一种方法。
基本上,挑战是这样的:给定一个在一个类中执行,这个类不是一个视图控制器(或一个视图)[并且没有活动视图的地址],并且没有传递最顶层视图控制器的地址(或者,比如说,导航控制器的地址),是否有可能找到那个视图控制器?(如果是的话,是怎么做到的?)
或者,如果找不到,有没有可能找到最高处的风景?
我遇到了一些情况,现在,它将是方便的,能够找到“最顶层”的视图控制器(一个负责当前视图),但还没有找到一种方法。
基本上,挑战是这样的:给定一个在一个类中执行,这个类不是一个视图控制器(或一个视图)[并且没有活动视图的地址],并且没有传递最顶层视图控制器的地址(或者,比如说,导航控制器的地址),是否有可能找到那个视图控制器?(如果是的话,是怎么做到的?)
或者,如果找不到,有没有可能找到最高处的风景?
当前回答
你应该使用:
[UIApplication sharedApplication].window.rootViewController;
当[UIApplication sharedApplication]上有一个uiactionsheet时。keyWindow,这是不正确的使用keyWindow在这个答案中提到。
其他回答
另一个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)
}
我认为你需要一个公认的答案和@fishstix的组合
+ (UIViewController*) topMostController
{
UIViewController *topController = [UIApplication sharedApplication].keyWindow.rootViewController;
while (topController.presentedViewController) {
topController = topController.presentedViewController;
}
return topController;
}
Swift 3.0 +
func topMostController() -> UIViewController? {
guard let window = UIApplication.shared.keyWindow, let rootViewController = window.rootViewController else {
return nil
}
var topController = rootViewController
while let newTopController = topController.presentedViewController {
topController = newTopController
}
return topController
}
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
}
}
我认为Rajesh的解决方案几乎是完美的,但我认为从上到下遍历子视图更好,我改为如下:
+ (UIViewController *)topViewController:(UIViewController *)viewController{
if (viewController.presentedViewController)
{
UIViewController *presentedViewController = viewController.presentedViewController;
return [self topViewController:presentedViewController];
}
else if ([viewController isKindOfClass:[UITabBarController class]])
{
UITabBarController *tabBarController = (UITabBarController *)viewController;
return [self topViewController:tabBarController.selectedViewController];
}
else if ([viewController isKindOfClass:[UINavigationController class]])
{
UINavigationController *navController = (UINavigationController *)viewController;
return [self topViewController:navController.visibleViewController];
}
// Handling UIViewController's added as subviews to some other views.
else {
NSInteger subCount = [viewController.view subviews].count - 1;
for (NSInteger index = subCount; index >=0 ; --index)
{
UIView *view = [[viewController.view subviews] objectAtIndex:index];
id subViewController = [view nextResponder]; // Key property which most of us are unaware of / rarely use.
if ( subViewController && [subViewController isKindOfClass:[UIViewController class]])
{
return [self topViewController:subViewController];
}
}
return viewController;
}
}
使用下面的扩展抓取当前可见的UIViewController。适用于Swift 4.0及更高版本
Swift 4.0及以上版本:
extension UIApplication {
class func topViewController(_ viewController: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
if let nav = viewController as? UINavigationController {
return topViewController(nav.visibleViewController)
}
if let tab = viewController as? UITabBarController {
if let selected = tab.selectedViewController {
return topViewController(selected)
}
}
if let presented = viewController?.presentedViewController {
return topViewController(presented)
}
return viewController
}
}
如何使用?
let objViewcontroller = UIApplication.topViewController()