find top viewcontroller
extension UIApplication {
class func topViewController(base: UIViewController? = (UIApplication.sharedApplication().delegate as! AppDelegate).window?.rootViewController) -> UIViewController? {
if let nav = base as? UINavigationController {
return topViewController(nav.visibleViewController)
}
if let tab = base as? UITabBarController {
if let selected = tab.selectedViewController {
return topViewController(selected)
}
}
if let presented = base?.presentedViewController {
return topViewController(presented)
}
return base
}
}and use like
if let topvc = UIApplication.topViewController()
{
if topvc is HomeVC
{
let vc = topvc as! HomeVC
vc.updateGcmMessageButton()
}
}