public function send($filename, array $render = [],$subject = '审核通知')
{
    // Create the Transport
    $transport = (new Swift_SmtpTransport('host', 'port'))
        ->setUsername()
        ->setPassword()
    ;

   
    $mailer = new Swift_Mailer($transport);

    
    $message = (new Swift_Message($subject))
        ->setFrom([])
        ->setTo([])
        ->setBody()
        ->addPart($this->blade($filename, $render), 'text/html')
        ->attach(Swift_Attachment::fromPath('http://cdn.sweetsunnyflower.com/blog/images/featured-posts/1-1.jpg'))//这里是添加附件
    ;

    // Send the message
    return $result = $mailer->send($message);
}

/**
 * @return string
 */
public function blade($filename, array $render)
{
    $templates = League\Plates\Engine::create(__DIR__ . '/views');
    return $templates->render($filename, $render);
}