iOS 5 deep sleep prevention

Question

I'm trying to build an alarm app that can fire an alarm while in locked-screen mode (the app is in the foreground, but the screen is locked). The alarm has to be triggered by a NSTimer not by uilocalnotification.

In iOS 4 I used the 'play silent sound every 10 seconds' hack to prevent the app from going to deep sleep and the timer events worked fine. However, in iOS 5 this doesn't seem to work.

Any ideas? Or this should work and I'm doing something wrong?

Peter, are you using https://github.com/marcop/iPhoneInsomnia with volume set to 0.1? — Henrik Strand, Jan 17 '12 at 13:04
as a base - yes. There were some issues with the code however, so i've changed a few things. — Peter Sarnowski, Jan 18 '12 at 05:02
Quite a few things to make it more suited to my needs - the way it schedules the audio playback for example. But I think it started working after setting volume to non-zero value. — Peter Sarnowski, Jan 18 '12 at 11:07
See https://github.com/mruegenberg/MMPDeepSleepPreventer for a working implementation for iOS 5. — mrueg, Jun 15 '12 at 13:10

score 4 · Accepted Answer · answered Dec 22 '11 at 05:28

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It seems that you actually can use the 'play silent audio' hack in iOS 5, but the audio has to be audible meaning you can't play it at volume set to 0.0.

answered Dec 22 '11 at 05:28

Peter Sarnowski

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score 4 · Answer 2 · answered Feb 15 '12 at 20:44

You can use github.com/marcop/iPhoneInsomnia and set the volume to greater than 0, but it still doesn't work because the sound file is so short that the system kills your application before the timer is triggered and replays the sound. I solved this by setting the numberOfLoops of the audioPlayer to -1 (infinite repeat). Then it should work.

And you should also set the UIBackgroundMode plist key to an array of one string called "audio"

score 2 · Answer 3 · answered Dec 19 '11 at 12:51

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It's probably a dirty workaround, but in the past I have used the proximity sensor to turn off the screen instead of locking the phone. Simply place the phone upside down and the screen will turn itself off.

[[UIDevice currentDevice] setProximityMonitoringEnabled:YES];

This will allow you to retain full control over the device, while the screen does turn off.

answered Dec 19 '11 at 12:51

Tom van der Woerdt

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This is an interesting idea. Not really what I'm looking for, but useful none the less. – Peter Sarnowski Dec 19 '11 at 13:15
I like it! Will the app never go to locked-screen mode using this technique? – jimmystormig Jun 10 '12 at 21:00
No, never. It's what some other apps use as well. Do note that the battery still drains so eventually the phone will go into "locked" state. ;-) – Tom van der Woerdt Jun 11 '12 at 08:55

iOS 5 deep sleep prevention

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