How can I locally detect iPhone clock advancement by a user between app runs?

Question

A common exploit in casual games is to artificially advance the system clock to jump ahead in gameplay. How can such user clock advancement be detected by an app on an iOS

Answer 1

I was thinking about the fact that the CoreLocation stuff could do this if that part of the GPS data was exposed to you. However that got me thinking.

My only (far fetched) suggestion is to put something into background processing - which has to be for one of a small specific set of reasons, for example to track location in the background. As a side effect of that, try to detect a clock change on a regular timer. Apple might reject it as it may be clear that its not using the location information and its just a reason to exploit background processing.

Any solution not involving networking is so much harder to implement, I wonder why you're not using it.