获取当前显示的ViewController

extension UIApplication {
    /// 获取keywindow
    static var currentKeyWindow: UIWindow? {
        if #available(iOS 13.0, *) {
            return UIApplication.shared.connectedScenes
                .filter {$0.activationState == .foregroundActive}
                .compactMap {$0 as? UIWindowScene}
                .first?.windows
                .filter {$0.isKeyWindow}.first
        } else {
            return UIApplication.shared.keyWindow
        }
    }
}

extension UIApplication {
    /// 获取当前显示的控制器
    /// - Parameter base: 基础控制器
    /// - Returns: 当前显示的控制器
    class func topViewController(base: UIViewController? = UIApplication.currentKeyWindow?.rootViewController) -> UIViewController? {
        if let nav = base as? UINavigationController {
            return topViewController(base: nav.visibleViewController)
        }
        if let tab = base as? UITabBarController {
            if let selected = tab.selectedViewController {
                return topViewController(base: selected)
            }
        }
        if let presented = base?.presentedViewController {
            return topViewController(base: presented)
        }
        return base
    }
    class var topViewController: UIViewController? {
        return topViewController()
    }
}