I have an app that records audio that has been working fine for some time. It uses the low level AudioQueue/AudioSession APIs in iOS. But with a recent model (“4th generation”) iPod Touch, when the app starts recording the iPod dims the screen after a minute and then blacks out and locks after another minute. On pressing “home” and unlocking the app has been terminated.
Note that one can’t really debug this with Xcode since if the iPod is plugged into Xcode it won’t dim.
Did Apple change something in a recent version of iOS, or is there something odd about the newer iPod Touch models?
Added:
If I just look at the console log, the app is running fine until I see UserEventAgent[12] <Warning>: DEBUG: Changing screen blanked state: 1
Next I see that the recorder has received a stop command. This apparently was a result of a call from applicationWillTerminate or applicationDidEnterBackground.
(Actually, there are a couple of other <Notice> messages ahead of the UserEventAgent one, from SpringBoard — Posting 'com.apple.iokit.hid.displayStatus' notifyState=0 and “ultitouchHID: detection mode: 0->255.)
(And the app eventually crashes because it’s trying to shut down the recording session cleanly and the OS wants it to quit NOW. But this is well after things have gone sour.)
Will be investigating
UIApplication idleTimerDisabled
plist “Required background modes”
There is a change in behavior between iOS versions (don’t know exactly what version). Previously active audio applications would not be backgrounded, but now they are. Supposedly recording can still go ahead in background, but all UI activity must stop or one is shot unceremoniously.
Currently I’m trying to figure out how to deal with the new behavior, and that’s a different set of questions.