Reading iOS Battery Crash Logs: how long did my app run?

0 votes
asked Sep 11, 2017 by swanijam

I'm developing a sort of a kiosk that makes use of an iPad and an app called "Mobile VR Station" to display a panoramic augmented-reality video that aligns with the surrounding park.

We need the app to be able to run for at least 48 hours uninterrupted (while plugged into to a battery pack of course).

I left the iPad running the app over the weekend, and it had, expectedly, crashed from running out of juice sometime over the weekend.

Got a hold of the battery-crash log from the device, shown here:

{"bug_type":"120","os_version":"iPhone OS 10.3.1 (14E304)"}
Incident Identifier: 89779227-E5F1-45F1-861D-D4899F483E20
CrashReporter Key:   56f0e2f92d263fe25e49e36b471e37d52d731427
Date:                2017-09-10 13:19:15 -0400
OS Version:          iPhone OS 10.3.1 (14E304)

assertiond: Mobile VR Stati:226:25-957440C0-48C0-44AC-8FAD-1E46E28DD5C6 [CMSession.226."com.mgatelabs.Mobile-VR-Station"."MediaPlayback".isPlayingProcessAssertion] [0x11bd27530]   NoIdleSleepAssertion == 255, held for 00:00:01
assertiond: SpringBoard:51:51-A919E5AA-A831-475A-912A-9583B82238C0 [FBSystemApp] [0x11bd16a60]  NoIdleSleepAssertion == 255, held for 51:08:48
mediaserverd: com.apple.audio.sid:0x190aa, Mobile VR Statio(226), 'prim'(com.mgatelabs.Mobile-VR-Station).isplaying NoIdleSleepAssertion == 255, held for 24:47:38
mediaserverd: com.apple.audio.VAD [vdef] AggDev 1.context.preventuseridlesleep  PreventUserIdleSystemSleep == 255, held for 24:47:48

Foreground Applications: com.mgatelabs.Mobile-VR-Station 
Screen Brightness: 0.646422
Hardware Model: J96AP
Awake Time: 05:56:08 (21368)
Standby Time: 05:56:08 (21368)
Partial Charge: 0
Capacity: 1
Voltage: 3597 mV

Usually I would look lines "Held for ##:##:##" to determine how long something was running, but this time there are several lines like that with very different times.

I've come up with almost nothing trying to google how to read these logs, although most of it makes sense to me. I'm hoping to understand why these wildly different runtimes are being reported in the same battery crash report, and most importantly I need to know how long Mobile VR Station was running.

Thanks!

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