Rare, mystery high mobile data usage

[sobri909]

There was (or apparently still is) an iOS bug that sometimes results in high mobile data usage due to wifi triangulation.

Arc App suffered from this a couple of years ago. And with a bit of back and forth with Apple, we determined that it was due to Arc App's regular updating of geofences, which would result in Location Services resetting and forgetting all its wifi triangulation data, thus having to refetch it.

At that time the easiest solution was to just give up the geofences. Arc App didn't need them anyway. I also reduced the frequency of LocoKit's dynamic desiredAccuracy updating, because changing that value also appeared to trigger the iOS bug.

Since then I hadn't heard anything more about it, until last week.

An Arc App user who spends many hours driving every day has reported the bug again. Mysteriously, "Time & Location" under "System Services" had consumed around 2GB of mobile data in a month.

I don't have any other user reports of this bug resurfacing. But I vaguely recall that Apple never actually closed the bug report for it. So maybe they merely mitigated it, but the core problem still remains.

So there's investigating to be done!