我在CDModel.xcdatamodeld中创建了一个简单的实体’CDWorkout’,其中一个属性’name’. AppDelegate中的容器名称也是“CDModel”. “CDWorkout”的类Codegen是类别/扩展名.这是CDWorkout类的代码：

class CDWorkout: NSManagedObject {

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

@H_301_3@createWorkout函数从另一个viewController调用,上下文参数为container.viewContext但它立即崩溃并显示消息：

@H_301_3@Terminating app due to uncaught exception ‘NSInvalidArgumentException’,reason: ‘An NSManagedObject of class ‘Workout_Generator.CDWorkout’ must have a valid NSEntityDescription.’

@H_301_3@我忘记了什么？