Question

How can I examine a list of all active objects that inherit UIViewController?

I’d like to know if an instance of MyViewController exists. Ideally I can get this information in a callback in UIApplicationDelegate (for example application:didReceiveRemoteNotification:).

I’ve tried logging something like navigationController.viewControllers w/ no luck. I’ve also tried topViewController and modalViewController properties on navigationController.

Answer 1

If you know for a fact that your rootViewController is a UINavigationController, you can iterate through the array of viewcontrollers and test it for a class type

BOOL success = NO;
NSArray *viewControllersArray = self.navigationController.viewControllers;
for (id vc in viewControllersArray)
{
    if ([vc isKindOfClass:[MyViewController class]])
        success = YES; // Found it!
}