How can I pull information from a magento store into an iphone app?

See more:

C

PHP

MySQL

Objective-C

SQLite

I am trying to build my first iphone app for a local webshop in my area and I was wondering what the best way to go about doing this. I am a php programmer and I don't have any experience with Objective-c.

What I want to do is to pull the products and categories and display them in my app and then have the app update to check for new products in the future.

If possible it would be great to also implement payment methods directly into the app so customers can make purchases from the app directly.

Is there any sample code available I could make use of and where should I start, my main question is how to get the information from magento to the app?