Hi, if I go for a run using a GPS-tracking app on my iPhone and when I finish, I forget to turn the off the app, which continues using assisted-GPS indoors, what happens?
I know the GPS signal will be lost indoors, so does the phone try to connect to cell-towers, not just Wifi, to help re-find my location?
iPhone X, iOS 13
In iOS all apps get their location data/information from iOS location services. Location services uses whatever is a available to determine location to the best of its abilities - aGPS when available, cell towers if necessary, WiFi if necessary or Bluetooth microbeacons if available. It prioritizes those based on what’s available to best and most accurately determine location.
So as long as location services is enabled, aGPS will be used (by maps, your running app, Find My, etc) if it’s available. If it isn’t, then the other sources of data come into play.
But closing your app doesn’t disable aGPS, since it’s use is actually under the control of iOS and its location services module.
The GPS receiver is on all the time whether you are using a navigation app or not, as long as Location Services is enabled. This is not a battery drain problem as it uses very little energy; GPS is passive, it only listens, it never transmits.
Navigation apps use energy and data to download maps dynamically, but if you’re in one location they won’t do that either. So there is no reason to turn off a navigation app except possibly for privacy. Apple Maps is not a privacy risk, because they don’t share your data. However Google Maps saves your location and navigation data and maintains it in a database that they share with advertisers. And Waze is owned by Google. But that is while you are moving; if you stay in one spot they lose interest except to note the location.
if you really want to disable a navigation app even though there is no reason to you can kill it like you would any other app: How to force an app to close on your iPhone, iPad, or iPod touch - Apple Support
Those articles are referring to apps actively running in the foreground, or are simply way out of date. When you go inside, Find My, for example, does not “dials through all the different satellites looking for a signal”. For one thing, aGPS only knows about the satellites that are actually talking to the device, not about the ones in low earth orbit that are silent (so it does not have some list of satellites to cycle through). It simple switches to WiFi data, or cell tower data, or Bluetooth beacon information, or whatever is available. As the developers document outline, location services is simultaneously using data from all possible sources, and uses whats available. It does not endlessly search for data from sources that are not available.
Apps that display location are not selecting what data they get nor the source of that data (iOS does not allow them to do that) - they simply are able to request location data from iOS’s location services. And iOS location services will use whatever is available to pass data to the third party requesting app.
And all of these location data sources are passive - the device simply listens for what’s available. It is not actively pinging or seeking anything. Location services are simply not a power hog - unless using an app actively that is showing it mapped to data that is streamed from some server.
PS, in the past, I remember being able to see a list of participated threads, not just subscribed ones (ones with notifications turned on). Now I have to subscribe to a thread if I want to keep it on my "content page", and I cannot turn off notifications for specific individual threads.
Michael,
"aGPS when available, cell towers if necessary"
As far as I am aware, assisted-GPS includes the use of cell towers, i.e. they are not exclusive.
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Assisted-GPS on the iPhone: what happens when I go indoors?
