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

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)
//...
}

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

[![enter image description here][1]][1]

This gives you the correct entity access `MyStaticLibrary.MyManagedObject`

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

[1]:

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

it easy to answer to this question. without removed

@objc(Workout)

the solution is on documentary [Core Data Programming](

[To see links please register here]

) 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][1]


[1]:

[![enter image description here][1]][1]in your file modeldataClass
probably name of Class is incorrect cause before you change name something in your name class


[1]:

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

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.

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)!`

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
}

}

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")