How to use inapppurchase in iphone app?

I am familiar with inapppurchase that lets you use additional features of the app.But i have no idea how to give user extra features.I have following queries:

1. If i am showing 6 items to user from an array.If i made user purchase 4 additional items,them how will i show them to the user as i have fix 6 items in my array.Do i have to create a new app which has all 10 items in it ? or there should be all 10 items in the first app but shown only 6 and then increse array value if user purchase?
2. Does inapppurchase means adding new features to an appor just unlocking locked featues that were a开发者_如何学Golready inside the app but just disabled?

Thanks in advance!!!!!

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In most scenarios, the application comes with all of the content needed. In that case, the application simply 'unlocks' the purchased functionality. For applications that deal with application content that can simply be downloaded, this might not be the case (for example, a digital magazine). In your case though, it sounds like including all of the content in the application would be ideal (and the least-complicated way to accomplish your goal).

When the user launches the application, you can use the StoreKit API to determine what items they have access to - and set the application state accordingly. Be sure to read on how to verify store receipts:

http://developer.apple.com/library/mac/#documentation/NetworkingInternet/Conceptual/StoreKitGuide/VerifyingStoreReceipts/VerifyingStoreReceipts.html#//apple_ref/doc/uid/TP40008267-CH104-SW1