Swift get top view controller

TopViewController.swift

// MARK: Find top view controller
extension UIViewController {
    
    func topViewController(_ base: UIViewController?, _ nonPresented: Bool = false) -> UIViewController? {
        if let nav = base as? UINavigationController {
            return topViewController(nav.visibleViewController, nonPresented)
        }
        if let tab = base as? UITabBarController {
            if let selected = tab.selectedViewController {
                return topViewController(selected, nonPresented)
            }
        }
        if let presented = base?.presentedViewController {
            return topViewController(presented, nonPresented)
        }
        if let searchController = base as? UISearchController {
            return topViewController(searchController.searchResultsController, nonPresented)
        }
        if nonPresented, let presentingVC = base?.presentingViewController {
            return presentingVC
        } else {
            return base
        }
    }
    
    func topViewController(_ nonPresented: Bool = false) -> UIViewController? {
        return topViewController(self, nonPresented)
    }
    
    class func topViewController(_ nonPresented: Bool = false) -> UIViewController? {
        return UIViewController.root?.topViewController(nonPresented)
    }
    
    static var root: UIViewController? {
        return UIApplication.shared.mainWindow?.rootViewController
    }
}

extension UIApplication {
    
    var mainWindow: UIWindow? {
        if #available(iOS 13.0, *) {
            return UIApplication
                .shared
                .connectedScenes
                .flatMap { ($0 as? UIWindowScene)?.windows ?? [] }
                .last { $0.isKeyWindow }
        } else {
            return UIApplication.shared.keyWindow
        }
    }
}