How to Email NSManagedObject

Question

I'd like to take data from my iPhone app, and allow users to email it to other users of the app. I have the app data stored as an array of NSManagedObjects in CoreData. What is the best way to take this stored data and convert it to a file that can be emailed and imported by my app? This is the NSManagedObject Subclass for the data:

import Foundation
import CoreData

class People: NSManagedObject {

    @NSManaged var days: AnyObject
    @NSManaged var dayZero: Date
    @NSManaged var firstName: String
    @NSManaged var gender: String
    @NSManaged var lastName: String

}

What is the best way to take this stored data and convert it to a file that can be emailed and imported by my app?

Answer 1

Your question is very broad so this will only be a high level answer.

To send the data via email you will need to add your data as an attachment to the email. And since you want this attachment to be usable with your app (and possibly only your app), you need to define your own custom file extension, UTI, and mime type.

You will need to convert your managed object into Data that can be attached to the email. There are many possible ways to do this. The easiest is to use NSKeyedArchiver.

Once you have the data from the managed object, Use MFMailComposeViewController. Add the data as an attachment and a proper filename using your custom extension.

You need to configure your app to handle your custom file type so when a user selects the attachment in the Mail app on their iOS device, and your app is installed, your app is an option for opening the mail attachment.

Implement the proper UIApplicationDelegate method to handle being passed the email attachment. From the URL, load it into a Data object and use NSKeyedUnarchiver to retrieve the original data.

There are many individual pieces to this puzzle. Each one has been covered in more detail in other questions and answers here or via Google.