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
下面两个函数可以帮助在视图控制器堆栈中找到topViewController。以后可能需要自定义,但是对于这段代码来说,理解topViewController或viewcontroller堆栈的概念非常棒。
- (UIViewController*)findTopViewController {
id topControler = [self topMostController];
UIViewController* topViewController;
if([topControler isKindOfClass:[UINavigationController class]]) {
topViewController = [[(UINavigationController*)topControler viewControllers] lastObject];
} else if ([topControler isKindOfClass:[UITabBarController class]]) {
//Here you can get reference of top viewcontroller from stack of viewcontrollers on UITabBarController
} else {
//topController is a preented viewController
topViewController = (UIViewController*)topControler;
}
//NSLog(@"Top ViewController is: %@",NSStringFromClass([topController class]));
return topViewController;
}
- (UIViewController*)topMostController
{
UIViewController *topController = [UIApplication sharedApplication].keyWindow.rootViewController;
while (topController.presentedViewController) {
topController = topController.presentedViewController;
}
//NSLog(@"Top View is: %@",NSStringFromClass([topController class]));
return topController;
}
你可以使用[viewController Class]方法找出一个viewController的类的类型。
其他回答
iOS 4在UIWindow上引入了rootViewController属性:
[UIApplication sharedApplication].keyWindow.rootViewController;
你需要在创建视图控制器后自己设置。
另一个Swift解决方案
extension UIViewController {
static var topmostViewController: UIViewController? {
return UIApplication.sharedApplication().keyWindow?.topmostViewController
}
var topmostViewController: UIViewController? {
return presentedViewController?.topmostViewController ?? self
}
}
extension UINavigationController {
override var topmostViewController: UIViewController? {
return visibleViewController?.topmostViewController
}
}
extension UITabBarController {
override var topmostViewController: UIViewController? {
return selectedViewController?.topmostViewController
}
}
extension UIWindow {
var topmostViewController: UIViewController? {
return rootViewController?.topmostViewController
}
}
以下是对我有效的方法。
我发现有时候控制器在键窗口上是nil,因为键窗口是一些操作系统的东西,如警报等。
+ (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;
}
为了完成JonasG的回答(谁在遍历时遗漏了标签栏控制器),这里是我返回当前可见的视图控制器的版本:
- (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;
}
}
迅速:
extension UIWindow {
func visibleViewController() -> UIViewController? {
if let rootViewController: UIViewController = self.rootViewController {
return UIWindow.getVisibleViewControllerFrom(rootViewController)
}
return nil
}
class func getVisibleViewControllerFrom(vc:UIViewController) -> UIViewController {
if vc.isKindOfClass(UINavigationController.self) {
let navigationController = vc as UINavigationController
return UIWindow.getVisibleViewControllerFrom( navigationController.visibleViewController)
} else if vc.isKindOfClass(UITabBarController.self) {
let tabBarController = vc as UITabBarController
return UIWindow.getVisibleViewControllerFrom(tabBarController.selectedViewController!)
} else {
if let presentedViewController = vc.presentedViewController {
return UIWindow.getVisibleViewControllerFrom(presentedViewController.presentedViewController!)
} else {
return vc;
}
}
}
用法:
if let topController = window.visibleViewController() {
println(topController)
}