Root view controller in Swift

root-viewcontroller-in-swift.md

IOS 15

extension UIApplication {
    var firstKeyWindow: UIWindow? {
        return UIApplication.shared.connectedScenes
            .compactMap { $0 as? UIWindowScene }
            .filter { $0.activationState == .foregroundActive }
            .first?.keyWindow

    }
}

IOS 13

extension UIApplication {
    var firstKeyWindow: UIWindow? {
        return UIApplication.shared.connectedScenes
            .compactMap { $0 as? UIWindowScene }
            .filter { $0.activationState == .foregroundActive }
            .first?.windows

            .first(where: \.isKeyWindow)

    }
}

Before iOS 13

UIApplication.shared.keyWindow?.rootViewController
// Or
UIApplication.shared.windows.first?.rootViewController

Source and details

https://sarunw.com/posts/how-to-get-root-view-controller/