Attach an array of doubles to a mail in Swift

Question

I am trying to attach an array of doubles to a mail using the MFMailComposeViewController class. So far this is my code in the ViewController class:

func prepareMail(data:[Double]) {                
        // Compose the mail
        let mailComposer = MFMailComposeViewController()
        mailComposer.mailComposeDelegate = self
        mailComposer.setToRecipients(["mail@mail.com"])
        mailComposer.setSubject("subject")
        mailComposer.setMessageBody("Hello ", isHTML: false)

        // Name data files (accelerometer + label)
        let fileName = "file"

        if let dataToAttach = data {
            //Attach File
            mailComposer.addAttachmentData(dataToAttach, mimeType: "text/plain", fileName: "\(fileName)")
            self.present(mailComposer, animated: true, completion: nil)
        }
    }
}

This code raises the following message:

initializer for conditional binding must have Optional type, not [Double]

So here are my thoughts:

Option 1: Convert the array of doubles to a string and send it as a plain/text file. My intuition, however, tells me that this is not a nice solution. I am not a fan of parsing.
Option 2: Encode the array somehow and send it using another mimetype other than plain/text. I explored some options in IANA mime Types, but I am not familiar at all and do not know where to start with.

I am not sure how to proceed.

Update your question with your attempts to solve your issue using your two options. Update your question with whatever issues you are having with those attempts. — rmaddy, Aug 15 '17 at 18:58

score 1 · Accepted Answer · edited Aug 15 '17 at 19:04

Your problem is this line if let dataToAttach = data because your data is [Double] and can't be nil, so you don't need to check of is nil, or you can change the parameters type to [Double]? to avoid this compiler error.

Replacing this:

if let dataToAttach = data {
            //Attach File
            mailComposer.addAttachmentData(dataToAttach, mimeType: "text/plain", fileName: "\(fileNames[i])")
            self.present(mailComposer, animated: true, completion: nil)
        }

by this:

   func prepareMail(data:[Double]) {
    // Compose the mail
    let mailComposer = MFMailComposeViewController()
    mailComposer.mailComposeDelegate = self
    mailComposer.setToRecipients(["mail@mail.com"])
    mailComposer.setSubject("subject")
    mailComposer.setMessageBody("Hello ", isHTML: false)

    // Name data files (accelerometer + label)
    let fileName = "file"

    if let dataToAttach = data.map({String($0)}).joined(separator: "\n").data(using: .utf8)
    {
        mailComposer.addAttachmentData(dataToAttach, mimeType: "text/plain", fileName: "\(fileNames[i])")
        self.present(mailComposer, animated: true, completion: nil)
    }

}

will be enough.

Thanks guys! I am now testing adding this: let dataTx = Data(buffer: UnsafeBufferPointer(start: data, count: data.count)), which i found [here](https://stackoverflow.com/questions/24516170/create-an-array-in-swift-from-an-nsdata-object), since `Data` type is required as @rmaddy commented. — lucasrodesg, Aug 15 '17 at 18:59

Attach an array of doubles to a mail in Swift

1 Answers1