Create NSManaged Object subclass Errors

Hi.

I am really new to this ... so please bare with me ...I think that I am missing a step but I canot find anything that explains the many errors that I am seeing ......

1. Create a new iOS project ... iOS Single View application; language:Swift, and Use Core Data,
2. With the datamodel file, add an Entity 'Person' with two attibutes, age (int64) and name (string)
3. Editor Menu ... Create NSManagedObject Subclass... Next/Next/Create (boxes all ticked on the way through)
4. Two files are created both with errors all over the place.

The first file that is generated is 'Person+CoreDataClass.swift' :

import Foundation

import CoreData

@objc(Person)

public class Person: NSManagedObject {

}

There is one error in this file: 'Invalid redeclaration of 'Person' for the Public Class declaration.

The second file is 'Person+CoreDataProperties.swift':

import Foundation

import CoreData

extension Person {

@nonobjc public class func fetchRequest() -> NSFetchRequest<Person> {

return NSFetchRequest<Person>(entityName: "Person");

}

@NSManaged public var age: Int64

@NSManaged public var name: String?

}

There are 6 (six!) errors in this code ...

1. extrension generates: 'Person is ambiguous for type lookup in this context'
2. The public class function also generates 'Person is ambiguous for type lookup in this context'
3. Both @NSManaged lines reports that they are 'only allowed on an instance property or method';
4. As well as 'Extensions may not contain stored properties'

Why? ... or rather how can I have done something wrong so soon? ... all this code is generated by Xcode itself ...

Thanks.