How to create a CSV file from Core Data (swift)

Question

I\'m building an app with core data (1 entity with 5 attributes) that display in a tableView. Now i would like to export this data to a CSV file (so i can send this file with m

Answer 1

This is a concise way of doing all you want - you pass array of managed objects and a string that is CSV's filename. The method writes your CSV to a file. I believe you already have most of this in your code, the thing that is lacking are last two lines that just write a string into a new file in "Documents" directory.

func writeCoreDataObjectToCSV(objects: [NSManagedObject], named: String) -> String? {
    /* We assume that all objects are of the same type */
    guard objects.count > 0 else {
        return nil
    }
    let firstObject = objects[0]
    let attribs = Array<Any>(firstObject.entity.attributesByName.keys)
    let csvHeaderString = (attribs.reduce("",combine: {($0 as String) + "," + $1 }) as NSString).substringFromIndex(1) + "\n"

    let csvArray = objects.map({object in
        (attribs.map({(object.valueForKey($0) ?? "NIL").description}).reduce("",combine: {$0 + "," + $1}) as NSString).substringFromIndex(1) + "\n"
    })
    let csvString = csvArray.reduce("", combine: +)

    return csvHeaderString+csvString
}

Now, somewhere else in the code you need to create NSData from this string and add it to mail composer:

let csvString = .....
let data = csvString.dataUsingEncoding(NSUTF8StringEncoding)
let composer = MFMailComposeViewController()
composer.addAttachmentData(attachment: data,
          mimeType mimeType: "text/csv",
          fileName filename: "mydata.csv")

Then, do the usual stuff with the composer (set body, topic, etc) and present it to the user!

EDIT:

Edited the answer to better answer the question.