iPhone app for read values from remote DB and show them sorted in pages

I've a remote DB, using a web service that return XML file I've to show records. I app I'll have: - List of records from remote table 1 - List of records from remote table 2 - Filter page for choose items to sort and group - Settings page for set values to pass to web service - Rate feature for allow each user to apply a rate to each record. Using rate feature app will send user rate to WS, my WS will save this value in DB. If a user apply a second (or third... or....) rate to same record ... app will update record rate deleting old user rate value an creating new record rate.