Question

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?

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?

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

}

Answer 1

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

UIViewController *vc = self.window.rootViewController;

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.

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

EDIT:

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

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

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

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