IOS7+ Transactions Validation
Starting from IOS7 Apple has provided a new way to validate transactions that have been already made including purchasing your app from the app store.
The receipt for an application or in-app purchase is a record of the sale of the application and of any in-app purchases made from the application. You can add receipt validation code to your application to prevent unauthorised copies of your application from running. Refer to the license agreement and the review guidelines for specific information about what your application may and may not do to implement copy protection.
Receipt validation requires an understanding of cryptography and a variety of secure coding techniques. It's important that you employ a solution that is unique to your application.
At a Glance
There are two ways to validate receipts: locally and with the App Store. Compare both approaches and determine which is a better fit for your app and your infrastructure. You can also choose to implement both approaches.
Validating Receipts Locally
Validating locally requires code to read and validate a PKCS #7 signature, and code to parse and validate the signed payload.
Validating Receipts With the App Store
Validating with the App Store requires a secure connection between your app and your server, and code on your server to validate the receipt with the App Store.