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Convert existing iOS paid app to freemium model with in-app purchase

Asked 2010-09-17T13:18:36.840
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I currently have a paid app in the store. Apple have not allowed a 'lite' version to be submitted as well, so I have no choice but to update the current paid version to a freemium (with in app purchase) model. I have the problem of not loosing functionality for v1 users that have purchased the app the first time round.

Is there any way to determine if an application have been updated from a previously installed version so I can unlock the paid parts of the app?

Two similar questions (from a few months ago):

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

iPhone + upgrade existing paid application on app store to free application with In App purchase + what about the customers who have already purchased the paid application

ios in-app-purchase app-store
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I've been thinking about this problem for some time now. I have a substantial amount of customers that paid for my (in App Store terms) high-price niche-App and I'd hate having to tell them to re-purchase as I plan to migrate to an In-App Purchase model.

The idea I came up with (and I'll ask Apple support whether it's legal) is to phase out the current paid App but ship a last update for it that allows "unlocking" the In-App purchases of the new App based on the In-App model. I was thinking about a challenge response scheme:

  • User has installed paid App on his device
  • User installs new In-App App and opens it. The new App detects the paid version and offers to unlock the In-App purchases (on this device only of course and as long as the App isn't deleted)
  • The new App generates a nonce, signs it and calls the old App with it via an URL Scheme
  • The old App decrypts the nonce, adds +1 one to it and signs it again. Calls back to the new App via URL scheme
  • The new App validates the nonce and unlocks the features

The scheme can be easily implemented using a pre-shared key. It's of course a weakness on jail-broken devices, but then every App storing In-App receipts has those problems.

answered 2013-06-06T06:13:32.533

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