ios:如何显示"选择无线连接"弹出窗口？

let alertController = UIAlertController(title: nil, message: "选择无线连接", preferredStyle: .actionSheet)

let cancelAction = UIAlertAction(title: "取消", style: .cancel, handler: nil)
alertController.addAction(cancelAction)

let openSettingsAction = UIAlertAction(title: "打开设置", style: .default) { (_) in
    if let url = URL(string: UIApplication.openSettingsURLString) {
        UIApplication.shared.open(url, options: [:], completionHandler: nil)
    }
}
alertController.addAction(openSettingsAction)

if let viewController = UIApplication.shared.keyWindow?.rootViewController {
    viewController.present(alertController, animated: true, completion: nil)
}