如何在Swift中发送包含PDF附件而不是用户电子邮件的电子邮件？

let mailComposeViewController = MFMailComposeViewController()

mailComposeViewController.setSubject("邮件主题")
mailComposeViewController.setToRecipients(["recipient@example.com"])
mailComposeViewController.setMessageBody("邮件正文", isHTML: false)

if let pdfData = NSData(contentsOfFile: "path/to/pdf/file.pdf") {
    mailComposeViewController.addAttachmentData(pdfData as Data, mimeType: "application/pdf", fileName: "attachment.pdf")
}

mailComposeViewController.mailComposeDelegate = self

if MFMailComposeViewController.canSendMail() {
    self.present(mailComposeViewController, animated: true, completion: nil)
}

extension ViewController: MFMailComposeViewControllerDelegate {
    func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
        // 处理发送完成或取消发送的事件
        controller.dismiss(animated: true, completion: nil)
    }
}