在AppDelegate.m的屏幕上获取当前显示的UIViewController [英] Get the current displaying UIViewController on the screen in AppDelegate.m

问题描述

屏幕上的当前 UIViewController 需要通过设置徽章视图来响应来自APN的推送通知。但是如何在方法应用程序中获取 UIViewController ：didReceiveRemoteNotification ： AppDelegate.m ？

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 UIViewController ，它可能是 UINavigationViewController 或其他类型的视图控制器。我发现 UINavigationViewController 的 visibleViewController 属性可用于获取 UIViewController 在屏幕上。但如果它不是 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?

任何帮助表示赞赏！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

当你的控制器不是 UINavigationController 时，你也可以使用 rootViewController ：

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

UIViewController *vc = self.window.rootViewController;

一旦你知道了根视图控制器，那么它取决于你如何构建你的UI，但是你可能会找到一种方法来浏览控制器层次结构。

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.

如果你提供一些关于你定义你的应用程序的方式的更多细节，那么我可能会给出更多提示。

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

编辑：

如果你想要最顶层的视图（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];

虽然这个视图可能看不见甚至被其某些子视图覆盖......

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

再次，这取决于你的用户界面，但这可能会有所帮助......

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

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