Topmost View Controller

UIViewControllerExtension.swift

import UIKit

extension UIViewController {

    static var topmostViewController: UIViewController? { return UIApplication.shared.keyWindow?.topmostViewController }

    var topmostViewController: UIViewController? { return presentedViewController?.topmostViewController ?? self }

}

extension UINavigationController { override var topmostViewController: UIViewController? { return visibleViewController?.topmostViewController } }

extension UITabBarController { override var topmostViewController: UIViewController? { return selectedViewController?.topmostViewController } }

extension UIWindow { var topmostViewController: UIViewController? { return rootViewController?.topmostViewController } }