Swift CoreData subclass not working - core-data

Question

i know that this has been asked a couple of times but the usual solution does not seem to work for me. I created a CoreData entity and a subclass for it using <ProjectName>.<SubclassName> syntax as class name. Creating a new object like this:
let object = NSEntityDescription.insertNewObjectForEntityForName("User", inManagedObjectContext: CoreDataManager.sharedInstance.managedObjectContext) as User
println("-->\(object)<--")
object.setValue(12, forKey: "userID")
object.setValue("username", forKey: "username")
the console output:
although the object does not get printed in the console it seems to have been in some way created and setting a value on that object refers to a Core Data Object
when i use it without a subclass it works as expected (setting Class name back to default):
let object = NSEntityDescription.insertNewObjectForEntityForName("User", inManagedObjectContext: CoreDataManager.sharedInstance.managedObjectContext) as NSManagedObject
println("-->\(object)<--")
output:
Here's my subclass declaration:
import Foundation
import CoreData
class User: NSManagedObject {
#NSManaged var userID: NSNumber
#NSManaged var username: String
}
and here's the core data model form:
What's wrong with the code? Or do i miss anything?

Answer 1

For printing out the value of an NSManagedObject, do not use:
println(...)
But rather use:
NSLog(...)
Please find an example of using NSLog and an NSManagedObject below:
/**
* Called when the user clicks on the save button.
*/
#IBAction func saveTapped(sender: AnyObject) {
// Reference to our app delegate
let appDel: AppDelegate = UIApplication.sharedApplication().delegate as AppDelegate
// Reference MOC
let context: NSManagedObjectContext = appDel.managedObjectContext!
let en = NSEntityDescription.entityForName("List", inManagedObjectContext: context)
// Create instance of put data model and initialize
var newItem: List = List(entity: en!, insertIntoManagedObjectContext: context)
// Map our properties
newItem.item = textFieldItemName.text
newItem.quantity = textFieldQt.text
newItem.info = textFieldMoreInfo.text
// Save our context
var error: NSError? = nil;
if (context.hasChanges) {
if (!context.save(&error)) { // save failed
println("Save Failed: \(error!.localizedDescription)")
} else {
println("Save Succeeded")
}
}
NSLog("newItem: %#", newItem)
// Navigate back to root ViewController
self.navigationController?.popToRootViewControllerAnimated(true)
}
Note: I do not know the exact reason (bug, or implementation maybe ...) but it turns out that it does not print out a value when we use println(...) function, instead of that it returns an empty String.
Consequently I recommend to all of you guys to use NSLog(...) function instead of println(...) when you want to print out the value of an NSManagedObject.

Answer 2

If you print the expression CoreDataManager.sharedInstance.managedObjectContext twice, do you get a different pointer each time?
It sounds like the managed object context is getting deallocated right after you use it, which indicates that your CoreDataManager.sharedInstance.managedObjectContext property is returning a new managed object context every time, not the same one, or your sharedInstance property is returning a new instance every time.
A managed object's in-memory state is stored as a weak reference to a managed object context. When the context drops out from underneath you (e.g. it's no longer referenced and so is deallocated), your managed object's storage disappears.
A few good indicators that this is happening:
You haven't saved your managed object context yet but a newly created managed object prints as fault
You get weird errors when you try to set a property
You get weird errors when you try to retrieve a property you just set

Answer 3

Include the following at the top of your .swift file
import CoreData
The reason for not working is it doesn't know which library to reference.
Hope it helps

Answer 4

try creating it with this method :
let entityDescripition = NSEntityDescription.entityForName(“User”, inManagedObjectContext: managedObjectContext)
let user = User(entity: entityDescripition, insertIntoManagedObjectContext: managedObjectContext)