public function getAuthorizeUrl($api_settings = '',
                                    $callback_url = 'https://api.vk.com/blank.html', $test_mode = false)
    {
        $parameters = array(
            'client_id' => $this->app_id,
            'scope' => $api_settings,
            'redirect_uri' => $callback_url,
            'response_type' => 'code'
        );

        if ($test_mode)
            $parameters['test_mode'] = 1;

        return $this->createUrl(self::AUTHORIZE_URL, $parameters);
    }