Transition an existing paid for app to free version with In App Purchase

Question

I have existing users of a paid for app on the App Store. I\'d like to transition the app to a free app with unlock-able features. Is there a way to roll my existing users i

Answer 1

The most robust solution is to do receipt validation. If you do not have a server that your app is communicating with, you can do it on the device with the help of OpenSSL. (Check the WWDC videos on receipt validation for details.) The key point is that the receipt has an attribute that tells you at which version the user has originally purchased your app. Based on this information you can then unlock features for existing customers.