How do I check if an UIViewController is currently being displayed?

Question

How do I check if an UIViewController is currently being displayed?

My UIViewControllers are listening for NSNotifications - e

Answer 1

Check to see if it's attached to the window. If it's not nil it's in hierarchy which is attached to the screen (of course it could be off the bounds of the screen, covered by some other view or have the hidden flag set)

if (myViewController.view.window) {
  // I'm attached to the window
} else {
  // not attached to the window
}