How to know when user made change to settings bundle

Question

I let the user make changes to their settings in the settings area of the iphone. During the next network sync i\'d like to send the user changes to the server. But only if the

Answer 1

It's not that the question is too hard, it's just that there's not a simple way to do what you're asking. NSUserDefaults doesn't record a "last modified" date for each app's settings, at least as far as I can tell, so if the user changes some settings using the Settings app, there's not a good way to detect that other than to look at all the settings.

If you really need to do this, I think your best bet is to read the settings that you're interested in syncing into some data structure and calculating some sort of hash or checksum based on that structure. Compare that value to the value that you calculated the last time the app ran, and sync with the server if it's different. You can store that value in NSUserDefaults if you want, but make sure that you don't include it in the calculation.