iOS Significant Location Monitoring Only Monitors WiFi?

Question

Ok, I'm not sure if this question has been asked in specific, though I did do some searching first and nothing came up. I was reading the docs about Significant Location Monitoring, and came across this:

The significant-change location service provides accuracy that’s good enough for most apps and represents a power-saving alternative to the standard location service. The service uses Wi-Fi to determine the user’s location and report changes in that location, allowing the system to manage power usage much more aggressively than it could otherwise. The significant-change location service can also wake up an iOS app that is currently suspended or not running in order to deliver new location data. Blockquote

Now, I've read a number of times here on StackOverflow that this service in fact also monitors cell tower changes. If not, then does anyone have any experience with this service outside of a city? Does it give any location changes at all?

Thanks!

Answer 1

I've done a bunch of testing over the last week or so with significant location change monitoring, and I've concluded the following:

1)The quote I posted above is wrong. I've seen significant location change monitoring trigger outside the city.

2)It really depends on how dense cell towers are in a given area. I live in Calgary, and our cell density is less than most places. So I've noticed that this service will trigger in downtown every 500 - 1000 m or so. On the outskirts of the city, its generally once every 10-20 km. In areas of my city that aren't near the core, usually the rate is about 5 - 10 km.

3)The service should restart the app when it has been shut down without user shutting it down. This is supposed to happen when there is a significant location change. However, if the user shuts the phone down, and restarts it, the app will immediately be restarted. I think that the phone clears its list of cell ids, so when it restarts, it automatically believes there has been a large location change.