iphone - Approach regarding web service call restricted to the visible cell only -

To create a list component (a tab view) for the iPhone app, the list content must be dynamic (read from the web) Service or local file system) and The app should only receive content that is viewable in the list (table) view and will request more data from each scroll server (file system or web service). Content should be refreshed automatically every 30 seconds.

So far I've been successful in the Creine Table View in Dummy Data (from Aero). But what should I approach that requests the existing cell only to use web services, any guidance here would be greatly appreciated.

I will suggest the following steps to solve your problem. 1. Keep a data array and keep you singing the refreshing table, every thirty seconds, as you've already done.
2. Create a separate thread to call the web service and you update the array when the feedback is available.
Thus, even if the Internet is down or slow down for some time, your GUI will not be affected on this. 3. Ensure that your array is being synchronized between threads.
4. If the web service content is too large, keep the version number for the data and send the request with the current version number. So if the web service has updated the version of the data it will send you only updates or differences. Or all the data on this condition will send you that your current version is out of date.

If the answer is not relevant to posting more details, then I may have a better understanding of the problem.