I am using Unity and I developing an app for iOS. How do I implement in-app purchases that work world-wide?
Apple provides a framework for in-app purchasing in StoreKit. You can read the docs on it here. From their documentation:
Store Kit communicates with the App Store on behalf of your application. Your application uses Store Kit to receive localized information from the App Store about products you want to offer in your application. Your application displays this information to users and allows them to purchase items. When a user wants to purchase an item, your app calls Store Kit to collect payment from the user. Figure 1-1 shows the basic store model.
How to implement in-app purchasing is more involved than the format here permits, but the general areas that you're going to need to learn about are:
- Retrieving Product Information from the App Store
- Making a Purchase from the App Store
- Adding a Store to Your Application
- Verifying Store Receipts
- Testing your store
- Auto-renewable subscriptions (possibly).
Here are some additional resources you may want to look at: