How to know if a controller view is in the front screen?

I'm using EventBus. A child controller depends on the main controller, the child controller is calling the methods from the main controller. Now, I need to know how I can check whether the user is on main controller or not. I tried using ```onViewBound and onViewView```, but the onViewBound and onViewView get called only when the user opens the controller for the first time, if the user goes back to the previous controller the onViewBound and onViewView never get called.

Any thoughts?