What are some ways I can sync iPhone Game data between multiple devices?

Question

From the Getting Started with Game Center doc

A player might have the same Game Center enabled game loaded on multiple devices. If your
app has reported progress on an achievement from one device, note that the same
achievement progress data will be provided by Game Center on other devices where the user
plays your game. However, other game state maintained by your app may not be in sync and
should be handled accordingly.

I'm relatively new to iOS development and about to begin researching how to sync local game state data (i.e. which levels the player has completed, which levels the player is currently on, etc.) between the different hardware (iPhone, iTouch, and iPad) running my game and I was hoping I could get some insight from the SO users on some good ways to do this. Do I need to build a web service for this? Can iTunes be used to sync this data? Is there an API specifically built for this?

Thanks for your wisdom!

Answer 1

I think using a web serivice and making a JSON post and request would be a good route.

Answer 2

One suggested method by Apple is to use the Application Preferences, which is backed up by iTunes when the user syncs the phone.