How the In App Purchase Feature Works with Your iPad App
Apple offers the In App Purchase feature, which enables the app users to purchase virtual items directly from inside the app. If you're developing a game app with multiple levels or environments, or virtual property, consider adding the In App Purchase feature to your app to sell more levels, environments, or property.
In App Purchase collects only payment. It doesn't download the e-book, add the game level, or hand over the virtual property. You need to provide the additional functionality, including unlocking built-in features or downloading content from your servers.
You put the In App Purchase store directly in your app by using the Store Kit framework. The Store Kit framework connects to the App Store on your app's behalf to securely process the user's payments.
You use iTunes Connect to set up your products the same way you set up new apps. In App Purchase supports four types of products:
Content: You can offer game levels, virtual property, and characters; digital books and magazines; photos and artwork — in short, any content that can be delivered within your app.
Functionality: You can unlock or expand features you've already delivered in your app, such as a game that offers multiple smaller games for purchase.
Services: You can charge users for a one-time service, such as voice transcription — each time the service is used, In App Purchase processes it as a separate purchase.
Subscriptions: You can provide access to content or services on a subscription basis, such as a finance magazine or an online game portal. You're responsible for tracking subscription expirations and renewal billing — the App Store doesn't send out renewal notices for you.
Although the In App Purchase feature provides a general mechanism for creating products, everything else is up to you. You can't sell real-world goods and services, only digital content, functionality, services, or subscriptions that work within your app. No intermediary currency is allowed (such as a virtual world's currency), and you can't include real gambling (although simulated gambling is okay). And it goes without saying that pornography, hate speech, and defamation are not allowed.
In App Purchase divides the responsibilities of selling products between your app and the App Store, handling only the payment portion. Here's how it works: Your app retrieves the list of product identifiers (set up with iTunes Connect) from its bundle. The app sends a request to the App Store for localized information about the products. Your app then displays this information in a store format, so that users can purchase items. When a user elects to purchase an item, your app calls Store Kit to collect payment. Store Kit prompts the user to authorize the payment and then notifies your app to provide the items the user purchased.
This process is spelled out (in detail) in the In App Purchase Programming Guide, which you can find in the iPhone Dev Center.