Can I have iAds and In-app Purchase to remove ads in one single app?

Question

According to Apple Advertising guide: https://developer.apple.com/appstore/resources/approval/guidelines.html#advertising

I have confusion about the this point:

Answer 1

Yes, you are allowed to show Ads (iAd or anyone else') and turn them off if the user makes an In-Ap Purchase. There are no Terms of Service that disallow that.

One simplistic implementation would be to check a value saved in NSUserDefaults. If the value is NOT there show Ads, and if the value IS there do not. You set that value when the user makes the In-App purchase.