在 AppDelegate.m 中获取当前显示在屏幕上的 UIViewController [英] Get the current displaying UIViewController on the screen in AppDelegate.m

问题描述

屏幕上当前的 UIViewController 需要通过设置一些徽章视图来响应来自 APNs 的推送通知.但是如何在 AppDelegate.m 的方法application:didReceiveRemoteNotification: 中获取UIViewController?

The current UIViewController on the screen need to response to push-notifications from APNs, by setting some badge views. But how could I get the UIViewController in methodapplication:didReceiveRemoteNotification: of AppDelegate.m?

我尝试使用 self.window.rootViewController 来获取当前显示的 UIViewController，它可能是一个 UINavigationViewController 或某种其他类型的视图控制器.我发现 UINavigationViewController 的 visibleViewController 属性可用于在屏幕上获取 UIViewController .但是如果它不是 UINavigationViewController，我该怎么办?

I tried use self.window.rootViewController to get the current displaying UIViewController, it may be a UINavigationViewController or some other kind of view controller. And I find out that the visibleViewController property of UINavigationViewController can be used to get the UIViewController on the screen. But what could I do if it is not a UINavigationViewController?

感谢任何帮助！相关代码如下.

Any help is appreciated! The related code is as following.

AppDelegate.m

...
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {

    //I would like to find out which view controller is on the screen here.

    UIViewController *vc = [(UINavigationViewController *)self.window.rootViewController visibleViewController];
    [vc performSelector:@selector(handleThePushNotification:) withObject:userInfo];
}
...

ViewControllerA.m

- (void)handleThePushNotification:(NSDictionary *)userInfo{

    //set some badge view here

}

推荐答案

当您的控制器不是 UINavigationController 时，您也可以使用 rootViewController :

You can use the rootViewController also when your controller is not a UINavigationController:

UIViewController *vc = self.window.rootViewController;

一旦您知道根视图控制器，那么这取决于您构建 UI 的方式，但您可能会找到一种在控制器层次结构中导航的方法.

Once you know the root view controller, then it depends on how you have built your UI, but you can possibly find out a way to navigate through the controllers hierarchy.

如果您提供更多有关您定义应用的方式的详细信息，那么我可能会提供更多提示.

If you give some more details about the way you defined your app, then I might give some more hint.

如果你想要最顶层的view(不是视图控制器)，你可以检查

If you want the topmost view (not view controller), you could check

[[[[UIApplication sharedApplication] keyWindow] subviews] lastObject];

虽然这个视图可能不可见，甚至被它的一些子视图覆盖......

although this view might be invisible or even covered by some of its subviews...

同样，这取决于您的用户界面，但这可能会有所帮助...

again, it depends on your UI, but this might help...

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