I'm planning on implementing some in-app purchase items and I want to save purchase information/data such that iTunes will backup said information when my customers sync. The Apple provided documentation states that this is possible, but doesn't really tell you how.
Where/how do I save purchase history (let's say, a NSString for each item) such that iTunes will back it up on the next sync?
Lastly, how would you suggest that I test this before making all of this go live?
Thanks.
P.S. Right now I'm using NSUserDefaults to store this info.
NSUserDefaults is fine for storing that kind of thing, but you should also use StoreKit's “check for purchased items” capability—a lot of apps that use in-app purchases have a button somewhere that checks the “purchased” state of the available products and re-enables them in the app, in case a user uninstalls and then reinstalls the app or installs it on a different device.
Testing in-app purchases can be done using the sandbox environment—iTunes Connect will let you set up a test iTunes Store account which has free access to all of your app's in-app purchases.