How to know if my keywindow.rootViewController is an Alert? - ios

Question

I'm having a problem to find out if my keywindow.rootViewController is an UIAlertController object. This must be a very simple thing to do, but I don't know what is wrong with my code:
UIViewController *rootViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
if( [rootViewController isKindOfClass:[UIAlertController class]]){
// Do something
}
Why I never enter in that IF STATEMENT, even when I can see on the debug that the view of this controller is an _UIAlertControllerView*? There is any other way to check if my key window is an Alert?
Thanks.

Answer 1

I assume what you want to do is be able to check if an alert is showing from any view controller in your application, but you're not sure which controller is displaying the alert and don't have access to the alert itself.
I've had to deal with this a few times. In previous versions of iOS you were able to iterate through all the subviews of a window to check if an UIAlertView was on the top, but with the changes to alerts in iOS8 this not longer works because all the delegates are deprecated and apple now recommends you use UIAlertController instead of UIAlertView. In any case, all the techniques were dependent on using certain versions of iOS and I've found them to be extremely unreliable.
What I use now is a singleton that keeps track of how many alerts are displaying. The singleton has a method that returns the current number of alerts displaying, a method for adding one, and a method for subtracting one.
This is implemented by adding one to the singleton when you present the UIAlertController:
[self presentViewController:alert animated:YES completion:^(){
AlertSingleton *muhInstance = [AlertSingleton sharedInstance];
[muhInstance addOne];
//Anything else for completion
}];
And then subtracting one with every possible action choice you add to the alert like this:
UIAlertAction *myAction = [UIAlertAction actionWithTitle:#"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
AlertSingleton *muhInstance = [AlertSingleton sharedInstance];
[muhInstance removeOne];
//Any Other alert actions
}];
Now you can know anywhere in your application if an alert is showing by checking if the count in the singleton is greater than zero like this:
if ([[AlertSingleton sharedInstance] alertCount] > 0) {
//There is an alert showing
//Your code here
}
I've found this technique to be very reliable for tracking alerts.