How does it work? I get that you can be periodically woken up by iOS to run in the background for short periods of time. But how do you know if you've moved 1.0km or more before before being woken up? It makes sense that you wouldn't want to fire up the GPS equipment if you haven't moved... but there's a chicken-egg problem.
Or do you just record only if you've moved 1.0km or more? How often does the app check your location?
You hope ;) Significant location change is based on cell phone towers. The update only seems to happen when you switch towers or are switching between towers. Less towers = less accurate, more towers = more accurate.
You are totally correct. With iOS 4 the significant location changes API can be trusted with distances around 1 mile / 1.5 kilometers. Anything below that and you don't have any guarantee.
My first version was only using significant location changes and after a lot of users
feedback, the second release was improved dramatically by switching the way I was using the significant location changes API and some other GPS API: the app now has a better accuracy and the feedback from my users has almost disappear.
Anyway congrats for the OP to ship his app! Enjoy the ride in the AppStore.
Congratulations!
Second-
How does it work? I get that you can be periodically woken up by iOS to run in the background for short periods of time. But how do you know if you've moved 1.0km or more before before being woken up? It makes sense that you wouldn't want to fire up the GPS equipment if you haven't moved... but there's a chicken-egg problem.
Or do you just record only if you've moved 1.0km or more? How often does the app check your location?