Verifying the purchase (receipt) of another applic

Question

TL;DR: Is there a way to verify that a user has purchased another app (of mine) from the Mac App Store?

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In a brief, I want to completely rebrand one of my applications on the Mac App Store. The current version is very buggy and has a user base of nearly 90% pirates. I want to shut down the old application and completely rebrand it as a new product.

However, I don't want to completely screw over my current, legitimate customer base. I am hoping there is a solution to this. The way I was hoping to go about this was to:

• Create a new application – completely rebranded
• Make it free
• Have an In-App Purchase that unlocks the Pro version
• Allow customers of my previous app to "restore their purchase" to unlock the Pro version

The new app will have extensive anti-piracy measures. Furthermore, the current application requires a connection to one of my servers. When I release the rebranded app, I will shut down the current app.

I realize the forcing users to migrate may cause some backlash; however, I am hoping that, by providing the new and improved version 100% free, the backlash will pass.

Answer 1

• Look for the old app using NSBundle bundleWithIdentifier
• get the receipt of this bundle using appStoreReceiptURL
• validate the receipt
• unlock functionality

Bare in mind that the terms and conditions of Apple say something along the line of "only appstore IAP should be used to unlock features; don't roll your own license mechanism"