public function twitter()
    {
        if (is_null($this->title)) {
            $this->title = config('laravel-share.services.twitter.text');
        }

        $base = config('laravel-share.services.twitter.uri');
        $url = $base . '?text=' . urlencode($this->title) . '&url=' . $this->url;

        $this->buildLink('twitter', $url);

        return $this;
    }