Advice: Challenges while implementing iPhone In-App Purchase

I want to create an ebook store app which has in app purchase.

All the ebooks will contain images, sounds, text and XML file and will be stored on a web server.

XML file will contain mapping on what sound to play and what text to display on particular page.

1) Being a newbie for in-App Purchase, I would like to know whether I should download all images, sounds, text and XML together or one after another. Or what would be a better mechanism to download all these items?

2) I have read that Apple requires that if a user purchases an item through in-App purchase, all his devices should be able to access that purchased item. How do we ensure that?

Also, if you have experience related to similar project, can you please share the challenges that I might face and possi开发者_高级运维ble solution to it.

I really appreciate your advice.

Thank You.

1. I would compress all the files into one archive and then decompress them on the device. This will speed up the download and will also make your code a little simpler as you'd only need to download one file per ebook.

2. The StoreKit framework has methods for determining if a user has already purchased an item. If an ebook has already been purchased, then just have the app download it to the device. This is all documented in the StoreKit documentation.