Auto-Renewable In-App Purchases in iOS

Question

I am currently stuck implementing IAP for my App. Here is the basic information on how it works

• I am offering a one-year auto-renewable subscription to a service. The user will pay the IAP and they'll have access to the service.
• It should be possible for a user to purchase multiple subscriptions. It is possible (although unlikely) that the user will want to connect to two different services, so he should be able to pay for two subscriptions at the same time

That's the basic idea, sounds pretty simple. So I have followed Apple's instructions with great success, up until the point where paymentQueue:updatedTransactions gets called with the SKPaymentTransactionStatePurchased state. Here, several questions arise.

1. Apple's documentation shows that you should store transaction.transactionReceipt in NSUserDefaults. So I'm storing an array of these (since I want to support multiple, simultaneous subscriptions). The problem is that this has been deprecated in iOS7, so I don't know what to use instead.
2. The next problem is that I don't know what to do with this data. Once my App is killed and re-started, all I know is the size of my array in NSUserDefaults (e.g. there are two receipts, so two subscriptions have been purchased). However, how can I read the data in the receipt number to do some verification on my own server? How to I get the date range for which the subscription is valid? (I need to block access once the subscription is no longer valid, assuming the stop the auto-renew and it expires). All I have are NSData objects that I have no idea what to do with.

Thank you for your help!

Answer 1

You have a way to go. The purpose of saving the transaction.transactionReceipt was to submit it at some point in the future to the Apple servers. The Apple servers respond to a receipt by sending the latest receipt for that subscription. Now that transaction.transactionReceipt is deprecated, you get the receipt from the onboard receipt:

NSURL *receiptURL = [[NSBundle mainBundle] appStoreReceiptURL];
NSData *receiptData = [NSData dataWithContentsOfURL:receiptURL];

and either decode that (using OpenSSL and other C++ stuff) or, once again, send it to the Apple servers for decoding and responding.

An easier approach, and perhaps one more acceptable to App Review for a 'service', would be to use a non-renewing subscription. Non-renewing subscriptions can overlap so your problem with 2 services can be easily handled by the app.