how to track which purchase associated with a partiular game center user

Question

I am looking for advice on how to associate a purchase with a particular user, (for example, a game center user) basically the user who makes the purchase. The purchase is a consumable item or subscription, so it can't be restored.

My overall design using server product delivery mode is largely working, but it doesn't work with some edge or negative cases, when a transaction is interrupted. For example,

• gamecenter_user1 makes the purchase
• payment is made but app is terminated
• log in as gamecenter_user2 from game center app
• relaunch the app
• SKPaymentTransactionObeserver receives transation update
• gamecenter_user2 gets the purchase

Before making a purchase, I know the user who makes the purchase, and product identifier, I can save this information. However after receiving transaction or receipt from App Store, how do I identify the user who made this purchase?

Thanks

Answer 1

On the good side - I've heard of applications passing the devices UDID. I think this is pretty commonly done.

There are two downsides to this:

1. The UDID would not be persistant if someone changed devices.

2. People seem to be somewhat up-in-arms about the fact that applications are transmitting their UDID to outside servers without their knowledge. (I don't know why - but this freaks some people out - there's been news of it lately).