I'm making an app that needs to take a managed object array from core data and export it to a csv file that I plan to attach to an email being sent out using the mfMailComposer system. I have the data properly stored in the core data systems and the mail composer functionality seems to be working. I'm reaching a snag when I try to find the correct process by which to export the data.
I have already taken a long look at both of these posts attempting to determine a solution:
from 2012, seems very outdated: how to export Core Data to CSV
from 2016, more recent, but swift 3 and Xcode 8 have since been released and I worry this has become outdated as well: How to create a CSV file from Core Data (swift)
I have been attempting to try the solutions proposed in the second link, but much of the code gets marked as incorrect when typing it, so I believe it is now obsolete with the upgrade.
The code below is based off of the second post and therefore, likely outdated, but in order to provide a reference of the process I am trying to accomplish...
// Called by the press of xcode UI button
@IBAction func ExportToCSV(_ sender: AnyObject)
{
// Make our mail composer controller and fill it with the proper information
let mailComposeViewController = configuredMailComposeViewController()
// If the composer is functioning properly ...
if MFMailComposeViewController.canSendMail()
{
// ... Present the generated mail composer controller
self.present(mailComposeViewController, animated: true, completion: nil)
}
else
{
// ... Otherwise, show why it is not working properly
self.showSendMailErrorAlert()
}
}
// Used to set up the body of the outgoing email
func configuredMailComposeViewController() -> MFMailComposeViewController
{
// Establish the controller from scratch
let mailComposerVC = MFMailComposeViewController()
mailComposerVC.mailComposeDelegate = self
// Set preset information included in the email
mailComposerVC.setSubject("Generic email subject")
mailComposerVC.setMessageBody("Generic email body", isHTML: false)
// Turn core data for responses into a .csv file
// Pull core data in
var CoreDataResultsList = [NSManagedObject]()
// Register the proper delegate and managed context
let appDelegate =
UIApplication.shared.delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext
// Pull the data from core data
let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "ItemResponses")
do {
let results =
try managedContext!.fetch(fetchRequest)
CoreDataResultsList = results as! [NSManagedObject]
} catch let error as NSError {
print("Could not fetch \(error), \(error.userInfo)")
}
// Take the managed object array and turn it into a .csv sring to write in the file
let csvString = writeCoreObjectsToCSV(objects: CoreDataResultsList, named: "Generic name")
let data = csvString.dataUsingEncoding(NSUTF8StringEncoding)
mailComposerVC.addAttachmentData(data, mimeType: "text/csv", fileName: "GenericFilename.csv")
return mailComposerVC
}
// Takes a managed object and writes it to the .csv file ..?
func writeCoreObjectsToCSV(objects: [NSManagedObject], named: String) -> String
{
// Make sure we have some data to export
guard objects.count > 0 else
{
return ""
}
let firstObject = objects[0]
let attribs = Array(firstObject.entity.attributesByName.keys)
// The attires.reduce function is throwing an error about originally using combine as in the second post, used auto fix, but noteworthy.
//Now gives an error that says "No '+' candidates produce the expected contextual result type NSString"
let csvHeaderString = (attribs.reduce("", {($0 as String) + "," + $1 }) as NSString).substringFromIndex(1) + "\n"
// This function says that substring from index has been renamed as well as a few other lines within it
let csvArray = objects.map({object in
(attribs.map({((object.valueForKey($0) ?? "NIL") as AnyObject).description}).reduce("",combine: {$0 + "," + $1}) as NSString).substringFromIndex(1) + "\n"
})
// Again with the reduce issue
let csvString = csvArray.reduce("", combine: +)
return csvHeaderString + csvString
}
New the bottom of the code I have commented in the multiple errors with the suggested code from the second post and the issues pertaining after I use xCode's auto-fix feature.
I would like to thank you in advance for helping me with this issue. I am merely looking for the most up-to-date way to export core data as a .csv file and send it out. Thanks!
