在Swift中通过电子邮件发送文件

Question

我有csvString变量NSMutableString，我将此变量写入.CSV文件bpmonitor.csv。我想通过电子邮件发送此文件：

    var csvString = NSMutableString()
    csvString.appendString("Date;Time;Systolic;Diastolic;Pulse")

        for tempValue in results {

            var tempDateTime = NSDate()
            tempDateTime = tempValue.datePress
            var dateFormatter = NSDateFormatter()
            dateFormatter.dateFormat = "dd-MM-yyyy"
            var tempDate = dateFormatter.stringFromDate(tempDateTime)
            dateFormatter.dateFormat = "HH:mm:ss"
            var tempTime = dateFormatter.stringFromDate(tempDateTime)

            csvString.appendString("\n\(tempDate);\(tempTime);\(tempValue.sisPress);\(tempValue.diaPress);\(tempValue.hbPress)")
        }

let fileManager = (NSFileManager.defaultManager())
let directorys : [String]? = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory,NSSearchPathDomainMask.AllDomainsMask, true) as? [String]

        if ((directorys) != nil) {

            let directories:[String] = directorys!;
            let dictionary = directories[0];
            let plistfile = "bpmonitor.csv"
            let plistpath = dictionary.stringByAppendingPathComponent(plistfile);

            println("\(plistpath)")

            csvString.writeToFile(plistpath, atomically: true, encoding: NSUTF8StringEncoding, error: nil)

            var myMail: MFMailComposeViewController!

            if(MFMailComposeViewController.canSendMail()){

                myMail = MFMailComposeViewController()
                myMail.mailComposeDelegate = self

                // set the subject
                myMail.setSubject("My report")

                //Add some text to the message body
                var sentfrom = "Mail sent from BPMonitor"
                myMail.setMessageBody(sentfrom, isHTML: true)

                var testData: NSData = NSData(contentsOfFile: plistpath)

                myMail.addAttachmentData(testData, mimeType: "text/csv", fileName: "bpmonitor.csv")

                //Display the view controller
                self.presentViewController(myMail, animated: true, completion: nil)
            }
            else {
                var alert = UIAlertController(title: "Alert", message: "Your device cannot send emails", preferredStyle: UIAlertControllerStyle.Alert)
                alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))
                self.presentViewController(alert, animated: true, completion: nil)


            }
        }
        else {
            println("File system error!")
        }

我在第myMail.addAttachmentData(testData, mimeType: "text/csv", fileName: "bpmonitor.csv")行中有错误：

Cannot convert the expression's type '(NSData, mimeType: StringLiteralConvertible, fileName: StringLiteralConvertible)' to type 'StringLiteralConvertible'

我做错了什么？