On page 258 of part we add a call to center.requestAuthorization() when the switch is toggled on. I assume this means we no longer need to call center.requestAuthorization() in the appDelegate method didFinishLaunchingWithOptions. In fact it seems you must remove this call (in appDelegate) or the other call (in ItemDetail…) will never have any effect. This was not mentioned in the book as far as I can tell.
Page 238, “Remove the the local notification code from didFinishLaunchingWithOptions . . .” 
I know there’s a lot of stuff in the book and sometimes it’s easy to skip an instruction, but most of the time the book is correct.