将swift文件添加到应用程序的资源包时出现问题

对于我的应用程序,我需要能够发送电子邮件与各种类型的附件-直接从应用程序。我找到了一些解决方案并进行了测试。

这是我的代码:

import UIKit
import MessageUI

class ViewController: UIViewController, MFMailComposeViewControllerDelegate {
    var EmailTxt = ""

    override func viewDidLoad() {
        super.viewDidLoad()

        setEmailTxt()
        sendEmail()
        view.backgroundColor = UIColor.lightGray
    }

    func sendEmail() {
        if MFMailComposeViewController.canSendMail() {
            let mail = MFMailComposeViewController()
            mail.mailComposeDelegate = self
            mail.setToRecipients(["sgamesro@gmail.com"])
            mail.setMessageBody(EmailTxt, isHTML: true)
            mail.setSubject("test email")

            if let filePath = Bundle.main.path(forResource: "test", ofType: "swift") {
                print("# File path loaded.")

                if let fileData = NSData(contentsOfFile: filePath) {
                    print("File data loaded.")
                    mail.addAttachmentData(fileData as Data, mimeType: "swift", fileName: "test.swift")

                }
            }

            present(mail, animated: true)
        } else {
            // show failure alert
            print("# func sendEmail() Mistake")
        }
    }

    func setEmailTxt() {
        EmailTxt = "<p>test line 01</p> <p>test line 02</p>" //<p>This is some text in a paragraph.</p>
    }

    func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
        controller.dismiss(animated: true)
    }
}