Why does Settings->MyApp-Contacts on/off not work?

Page 222 of the iOS9 tut says:
Note: You should use the simulator instead of a real device to test your app in this chapter; you’ll have to reset your device in order to test the app permissions, and you don’t want to reset your personal iPhone, do you?

But on my actual device I have the switch and regardless of off or on the app fails to respond to my saying “ON”

Surely as I previously selected “OFF” does not mean I really have to reset my phone? If thats the case…what is the point of having the switch in the first place?

There are basically three settings for any device permission: either the user has permitted it, or they have denied it, or they haven’t answered the question yet.
When the user installs an app for the first time and the app tries to access a device permission, it checks this setting; if the user hasn’t answered the question then it prompts the user for permission, and if the user has answered the question then it trusts the ON/OFF in the settings.
The point of resetting the device is to restore it to the state where the user hasn’t answered the question, so you can test that your app asks for permission.