Best way to store data for an iPhone calendaring app

I am working on an iPhone app. It is a Enterprise calendaring app for my agency. We have a RESTful API backend connected to a web application where the appointments are entered. The appointments for an individual are to show up on that user’s iPhone. Data is sent by XML. There are only 3 or 4 appointments per day and less than 10 fields per record, so not a lot of data is transferred at a time (just the selected day’s information).

I tried to design this with an array on the iPhone for the parsed data, but the security checking on the web server makes the application time out when loading the data, and I didn’t handle the asynchronous processing well.

Now I’m wondering if I’m even approaching the problem correctly. Would it be better to use Core Data to store the appointments and then work to update the Core Data store in the background? I know I need to update the data outside of the loading the table process. I’m just at a loss for the best way to approach this.

I have looked through the site for information as to how to approach this. I have tried looking in books. Any help would be appreciated.