Update for Xcode 8:
In Xcode 8, one needs to go to the Core Data Model Editor and Show the File Inspector. Near the bottom is an option for code gen
Alternatively, you can just add #import "Person.h" to the bridging header, Project-Bridging-Header.h that Xcode generates for you (if you accepted it's offer to generate). Then you can use all the auto-generated Obj-C as if it were native Swift.
#import "Person.h"
Project-Bridging-Header.h