topViewController in iOS 12 / Xcode 10

Question

So, I've updated to Xcode 10 and iOS 12 today and now I'm getting the following error message when I call topViewController from UINavigationController:

Ambiguous use of 'topViewController'

if let myVC = navigationController.topViewController as? MyViewController {}

Even though the following code works just fine.

if let myVC = navigationController.visibleViewController as? MyViewController {}

Does anyone know any changes in iOS 12 regarding this?

Answer 1

I can suggest you this func for getting topViewContoller as an extension. Easy to use as you guess.

extension UIApplication {
    class func topViewController(controller: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
        if let navigationController = controller as? UINavigationController {
            return topViewController(controller: navigationController.visibleViewController)
        }
        if let tabController = controller as? UITabBarController {
            if let selected = tabController.selectedViewController {
                return topViewController(controller: selected)
            }
        }
        if let presented = controller?.presentedViewController {
            return topViewController(controller: presented)
        }
        return controller
    }
}

Usage:

UIApplication.topViewController()