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?

the topViewController is not change in iOS12. I tested in Xcode10, iOS12 and it has nothing wrong. What is your `navigationController`? — Quoc Nguyen, Sep 19 '18 at 03:59
do you have another variable with the name `topViewController`? — ahbou, Sep 19 '18 at 10:58
Actually there is a class that extends `UINavigationController` and an extension of `UIViewController` that has a variable called `topViewController`. It's legacy code so I'm not sure why it was created like this. But what changed in Xcode 10/iOS 12 that made this code doesn't work anymore? — edmoks, Sep 19 '18 at 13:14

score 2 · Accepted Answer · answered Sep 22 '18 at 15:01

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()

topViewController in iOS 12 / Xcode 10

1 Answers1