Lets have a look on the Objective-C way:

Person.h (Header-File)

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

@interface Person : NSManagedObject
@property (nonatomic, retain) NSString *name;
@end

Person.m (Implementation-File)

#import "Person.h"

@implementation Person
@dynamic name;
@end

Swift

The documentation already included in Xcode6-Beta says:

Core Data provides the underlying storage and implementation of properties in subclasses of the NSManagedObject class. Add the @NSManaged attribute before each property definition in your managed object subclass that corresponds to an attribute or relationship in your Core Data model. Like the @dynamic attribute in Objective-C, the @NSManaged attribute informs the Swift compiler that the storage and implementation of a property will be provided at runtime. However, unlike @dynamic, the @NSManaged attribute is available only for Core Data support.

So that is how I would rewrite the above example for Swift (not tested):

Person.swift

import CoreData

class Person: NSManagedObject {

    @NSManaged var name : NSString

}

And according to your question I think the subclass-generation-feature might be not included in Xcode6 yet. Did you made sure that you have chosen “Swift” as programming language when you were creating the Cocoa-Project in Xcode?