'An NSManagedObject of class 'className' must have a valid NSEntityDescription.' error

Question

I've created simple entity 'CDWorkout' with one attribute 'name' inside CDModel.xcdatamodeld. Name of container in AppDelegate is also 'CDModel'. Class Codegen for 'CDWorkout' is Category/Extension. Here is code for CDWorkout class:

class CDWorkout: NSManagedObject {

    class func createWorkout(workoutInfo : Workout, in context: NSManagedObjectContext) -> CDWorkout{
        let workout = CDWorkout(context: context)
        workout.name = "anyName"
        return workout
    }
}

the createWorkout function is called from another viewController with context argument as container.viewContext but it immediately crashes with message:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'An NSManagedObject of class 'Workout_Generator.CDWorkout' must have a valid NSEntityDescription.'

What did i forget about?

Answer 1

The issue I had was that I needed to have the Class Module set to Current Product Module for my CDWorkout Entity.

In Xcode 10 there is a drop down in the Class section of the Data Model Inspector.

Answer 2

I had a silly minor issue that resulted in the same error. I was initializing NSPersistentContainer with the incorrect name.

It should have the same name as the source file with the extension .xcdatamodeld. e.g. modelFileName.xcdatamodelId

let persistentContainer = NSPersistentContainer(name: "modelFileName")

Answer 3

In my case the same problem was in @objc modifier in auto-generated header of data-class

@objc(CachedMovie)
public class CachedMovie: NSManagedObject {

I just removed @objc(CachedMovie) and it began to work

Answer 4

I came across this same error message when trying to insert/add a managed object from an extension (SiriKit). It seems to have been an issue with the namespace of the extension not matching the .xcdatamodeld file, because I was creating the entity description using MyClass.entity().

The combination that worked for me was:

• @objc(MyClass) at the top of each NSManagedObject subclass
• Entities in the data model use the default "Global namespace", not "Current Product Module"
• Create the entity description using let entity = NSEntityDescription.entity(forEntityName: "MyClass", in: context)!

Answer 5

In AppDelegate check persistent container name. let container = NSPersistentContainer(name: "CoreData")

If you trying to reach nonexistent Core Data, that may manifest as this error.

Name should be exact same as .xcdatamodeld object in navigation menu.

GL :)

Answer 6

If you are using coreData from a static library make sure you specify the module aswell

This gives you the correct entity access MyStaticLibrary.MyManagedObject

So if your receiving warnings with this dot notation, its not looking in your module

Answer 7

One way this could happen is by trying to rename your entities. Make sure that these are the same!

Answer 8

For me, I forgot to add @objc(Reminder) in this below example. I wrote the NSManagedObject class programmatically.

@objc(Reminder)
public class Reminder: NSManagedObject {


}

Answer 9

I encountered this issue using Swift Package Manager to import a Swift Package that had a model file included as a resource. In my case setting the Module of my entity to Current Production Module produced an incorrect value in the model file. When I used the debugger to print the model after loading the persistent container the fully qualified class name was something like Module_Module.Class instead of the expected Module.Class. I had to manually type the module name instead of using Current Production Module to resolve the issue.

Answer 10

in your file modeldataClass probably name of Class is incorrect cause before you change name something in your name class

Answer 11

The mistake I made was to change the name of the entity and the generated "NSManagedObject Subclass" and not updating the name of the class. How to fix:

• open .xcdatamodeld
• click on the entity
• open the right panel
• Go to Data Model Inspector
• Change the name of the Class text field

Answer 12

I've got the same issue. In my case I used CoreData initialised and managed in framework wich I integrated with main app via SPM.

Solution

First, in the framework provide module name for entity by hand, by following steps:

1. open .xcdatamodel,
2. select Entity which you want to edit,
3. open Data Model Inspector (the 4th panel in right sidebar),
4. at section Class element Module by default presents Current Product Module -- enter here your Module name

Repeat these steps for each entity.

Second, in the framework override description for each NSManagedObject you use in project, f.ex. you have:

public class Person: NSManagedObject {

}

override there description with String without module name, like:

public class Person: NSManagedObject {

    public override var description: String {
        return "Person"
    }
}

Code presented above will help if you use convenience initialiser for Person (like Person(context: Context)) which uses description to specify Person.entity().

Answer 13

I had similar issue in CoreData stack with NSManagedObjectModel made from Swift code. The issue was in wrong value for NSEntityDescription.managedObjectClassName attribute. The Swift module prefix was missed.

Correct setup:

let entity = NSEntityDescription()
entity.name = PostEntity.entityName // `PostEntity`
entity.managedObjectClassName = PostEntity.entityClassName // `MyFrameworkName.PostEntity`
entity.properties = [....]

Where: entityName and entityClassName defined like this.

extension NSManagedObject {

    public static var entityName: String {
        let className = NSStringFromClass(self) // As alternative can be used `self.description()` or `String(describing: self)`
        let entityName = className.components(separatedBy: ".").last!
        return entityName
    }

    public static var entityClassName: String {
        let className = NSStringFromClass(self)
        return className
    }

}

Answer 14

I was trying out adding CoreData to existing project and I renamed things a lot. I ended up with multiple .xcdatamodeld without knowing it. The solution was removing .xcdatamodeld and generated NSManagerObject and recreating it again.

Answer 15

it easy to answer to this question. without removed

@objc(Workout)

the solution is on documentary Core Data Programming on "Entity Name and Class Name". here in your Xcode before doing (Editor -> Create NSManagedObject SubClass) must change your class Name of Entities to add "MO", CoreData can differentiate between class Name and Entitie Name. and the

@objc(Workout) 

will not be created, give us this one:

class CDWorkoutMO: NSManagedObject {

 class func createWorkout(workoutInfo : Workout, in context: NSManagedObjectContext) -> CDWorkoutMO {
    let workout = CDWorkoutMO(context: context)
    workout.name = "anyName"
    return workout
}
}

like I do on my Xcode

Answer 16

For SwiftUI you need to also update this method from SceneDelegate:

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    //This gets the context from AppDelegate and sets is as moc environment variable
    let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    let contentView = ContentView().environment(\.managedObjectContext, context)
    //...
}