func getLastVisibleController(ofParent parent: UIViewController? = nil) -> UIViewController? {
    if let vc = parent {
        if let tab = vc as? UITabBarController, let selected = tab.selectedViewController {
            return getLastVisibleController(ofParent: selected)
        } else if let nav = vc as? UINavigationController, let top = nav.topViewController {
            return getLastVisibleController(ofParent: top)
        } else if let presented = vc.presentedViewController {
            return getLastVisibleController(ofParent: presented)
        } else {
            return vc
        }
    } else {
        if let rootVC = UIApplication.shared.keyWindow?.rootViewController {
            return getLastVisibleController(ofParent: rootVC)
        } else {
            return nil
        }
    }
}