Magento 2.3 Mail Transport add Attachments

magento2.3-send-mail-with-attachments.php

<?php

$emailData = [ ... ];

/* @var $transportBuilder \Magento\Framework\Mail\Template\TransportBuilder */
/* @var $transport \Magento\Framework\Mail\Transport */

$transport = $transportBuilder->getTransport();
if (isset($emailData['attachments']))
{
    $parts = $transport->getMessage()->getBody()->getParts();
    foreach ($emailData['attachments'] as $item)
    {
        $attachment = new \Zend\Mime\Part($item['content']);
        $attachment->type = $this->getContentTypeByName($item['name']); // define content type. eg. application/pdf
        $attachment->filename = $item['name'];
        $attachment->disposition = \Zend\Mime\Mime::DISPOSITION_ATTACHMENT;
        $attachment->encoding = \Zend\Mime\Mime::ENCODING_BASE64;
        $parts[] = $attachment;
    }
    $bodyPart = new \Zend\Mime\Message();
    $bodyPart->setParts($parts);
    $transport->getMessage()->setBody($bodyPart);  
}