I am trying to build a document based SwiftUI application with core data enabled. Starting from the template in Xcode (11.5): New project -> macOS + App -> Swift + SwiftUI + "Create document-based application" + "Use Core data". After that I try to add an entity in model editor with just two attributes, "id" and "amount". The entity is called "Trans" and codegen is set on "Class Definition". In the provided Content view I add the code below so I can access the managed object context. @Environment(\.managedObjectContext) var moc So far it's working as expected. After that I try to add a simple fetch request. @FetchRequest(entity: Trans.entity(), sortDescriptors: []) var trans: FetchedResults<Trans> Then this error comes up in the console. No NSEntityDescriptions in any model claim the NSManagedObject subclass 'myapp.Trans' so +entity is confused. Have you loaded your NSManagedObjectModel yet? I am quite new to Core Data so I don't even know where to start looking. Is this broken? Or am I supposed to add more code to get it to work? Can someone please point in the right direction?