CODEWITHSUNDEEP
iosbackgroundgpslocationpower-management
Andy
Andy

Reputation: 446

Reducing iOS Background Location Battery Usage

I'm working on an iOS app that ideally needs to run the location services in the background. I've tested the significant location, and that isn't accurate enough. The accurate location is perfect, but this consumes far too much battery life to make the app viable.

To get around this battery issue I thought I'd found a solution that uses NSTimer inside UIApplication:beginBackgroundTaskWithExpirationHandler:. This turns the location on and then instantly off again, which triggers a location update and resets the backgroundTimeRemaining.

However, this solution still drains a lot of battery – 15%-20% every 3-4 hours – even when the location is only turned on for one second every 9 minutes. The app is not running anything else in the background aside from this one timer. I've even tried releasing all of the views when entering the background to make sure there is nothing sitting and consuming the battery.

Checking inside instruments, I found the app is using 0.0% of the CPU and 14 MB of memory while in this waiting state. I'm at a bit of a loss at this point as to the cause, especially since running the GPS for 1 second every 540 seconds does not provide an appreciable reduction in battery consumption, compared to running it 24/7.

I've started compiling the following questions, which might contribute to the problem, and I'm hoping somebody has an answer or an idea...

Upvotes: 19

Views: 4595

Answers (1)

GregularExpressions
GregularExpressions

Reputation: 523

Yes, WWDC 2011 Session 312 "iOS Performance and Power Optimization with Instruments" covers this at about the 45 minute mark.

When you finish using the GPS it can remain active for up to 10 seconds, and active radios both wake the device and while active prevent the device from 'sleeping'.

You'll be able to see this using the 'Energy Diagnostics' template in Instruments.

Upvotes: 2

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