我有真正的误解与MFMailComposeViewController在Swift(iOS8)在模

按钮“取消”不工作。在控制台中几秒钟后出现：

viewServiceDidTerminateWithError: Error Domain=_UIViewServiceInterfaceErrorDomain Code=3 "The operation couldn’t be completed. (_UIViewServiceInterfaceErrorDomain error 3.)" UserInfo=0x7f8409f29b50 {Message=Service Connection Interrupted}

<MFMailComposeRemoteViewController: 0x7f8409c89470> timed out waiting for fence barrier from com.apple.MailCompositionService

有我的代码：

func actionSheet(actionSheet: UIActionSheet!,clickedButtonAtIndex buttonIndex: Int) {
    if buttonIndex == 0 {
        println("Export!")

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

        for tempValue in results {     //result define outside this function

            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 testData: NSData = NSData(contentsOfFile: plistpath)

            var myMail: MFMailComposeViewController = 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)

                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,completion: nil)


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

尝试改为使用UIActivityViewController发送邮件：

let fileURL: NSURL = NSURL(fileURLWithPath: plistpath)
let actViewController = UIActivityViewController(activityItems: [fileURL],applicationActivities: nil)
self.presentViewController(actViewController,completion: nil)

看到大致相同的屏幕发送电子邮件，一会儿后返回到上一个屏幕。在控制台中，现在又出现了另一个错误：

viewServiceDidTerminateWithError: Error Domain=_UIViewServiceInterfaceErrorDomain Code=3 "The operation couldn’t be completed. (_UIViewServiceInterfaceErrorDomain error 3.)" UserInfo=0x7faab3296ad0 {Message=Service Connection Interrupted}
Errors encountered while discovering extensions: Error Domain=PlugInKit Code=13 "query cancelled" UserInfo=0x7faab3005890 {NSLocalizedDescription=query cancelled}
<MFMailComposeRemoteViewController: 0x7faab3147dc0> timed out waiting for fence barrier from com.apple.MailCompositionService

有关于PlugInKit的东西。

使用UIDocumentInteractionController改为UIActivityViewController：

let docController = UIDocumentInteractionController(URL: fileURL)
docController.delegate = self
docController.presentPreviewAnimated(true)
...

func documentInteractionControllerViewControllerForPreview(controller: UIDocumentInteractionController!) -> UIViewController! {
    return self
}

我看到这个屏幕与内容的CSV文件：http://prntscr.com/4ilgax我按右上角的按钮导出，看到这个屏幕http://prntscr.com/4ilguk在那里我选择MAIL和几秒钟我看到http://prntscr.com/4ilh2h然后返回显示文件的内容！在控制台中使用与使用UIActivityViewController时相同的消息。