Assisted-GPS on the iPhone: what happens when I go indoors?

That is all nonsense. Listening for GPS uses virtually no energy. And has nothing to do with mapping apps. The ONLY way to disable GPS is to turn off location services. It doesn’t matter if any mapping apps are running or not. GPS is on when location services are on.

indoors the phone will use more energy, but that has nothing to do with GPS. It’s because when the CELLULAR signal is weak the phone must increase its transmitting power to remain synced to the network. If the network connection is 1 bar the phone requires 10 times as much transmitter power as it does with 5 bars. And if you lose cellular signal entirely the phone will use enormous amounts of power trying to reconnect for about 5 minutes, then it will shut down the cellular radio entirely for 5 minutes and then try again. So the phone does go into random search mode, but it is searching for the cellular network, not GPS. The .5 w to 1.5 watts is correct but that is for cellular network searching, not GPS. Whoever wrote that article is really clueless and is confusing cellular network connectivity with GPS.

With the current national lockdown I am indoors an average of 23 hours a day; my phone’s battery life has never been better. I charge it overnight every night, and at the end of the day my state of charge is still around 80%. If that article was correct my battery would be dead by noon, because I never shut down any apps, mapping or otherwise. And I have no GPS visibility indoors. No one does, actually; GPS needs an unobstructed view of the sky. You don’t need a Walmart to block it; any roof will do.

This is from the developers documentation -> https://developer.apple.com/documentation/corelocation/

“Overview

Core Location provides services that determine a device’s geographic location, altitude, and orientation, or its position relative to a nearby iBeacon device. The framework gathers data using all available components on the device, including the Wi-Fi, GPS, Bluetooth, magnetometer, barometer, and cellular hardware.”

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

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.

Well, your phone pings cell towers regularly whether you are using GPS or not. That’s so when you get a call the network knows which towers you are connected to.

But it doesn’t ping cell towers for location information, it just listens for network traffic.

No, you will have to take my word for it as a former network engineer. But as long as you have location services enabled for any app at all (Find My, for example) the phone will use whatever it needs to “know” it’s location. It only listens, as I said; it never “pings” anything for location determination. And read Michael Black’s post also.

The network always knows approximately where you phone is (within about 1/4 mile), and so does any government agency or law enforcement authority who wants that information. And the carriers also sell that information to anyone who will pay them; businesses, advertisers, political campaigns, etc. but none of that requires that your GPS app be running.

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.

Cell towers are not an accurate source of location data, but Wi-Fi is. So you should leave Wi-Fi on all the time.