As you may have seen from other threads I'm learning iPhone development by writting my first app. The app uses Core Data to store items from an XML file. What I want to be able to do is read that same XML file at a later date and compare if the items are the same against the one's in core data and if not leave the item if the same, remove if it isn't in the new XML or add if it's a new item. For example the mail application (my app isn't a mail one), after the initial load it will download new emails, leave ones that are still there or delete one's I have deleted via a front end (GMail). So my question is, is it possible? If so are there any good examples people are aware of?