Audio triggered by background location - ios

Question

Target OS: iOS 6+
Devices: Phones only
I'm creating an fairly simple locative media app. The one technical difficulty I'm having is whether or not I can do what I want with background audio.
I receive GPS location updates successfully in the background but I would like to use these to trigger audio on region entry. The app does not play audio constantly in foreground, only on entry to these fences.
Does the 'playing silence' trick still work to keep the Audio Session and is this an app where Apple would tolerate its use? If so could anyone provide recently functional code for it?

Answer 1

If you set up your application to also enable background audio, in application:didFinishLaunching: like so:
[[AVAudioSession sharedInstance] setDelegate: self];
[[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayback error:nil];
[[AVAudioSession sharedInstance] setActive:YES error:nil];
and add audio as a background mode in the app's plist file, your app will keep on running in the background and play sounds when it wishes (e.g. when a location change has happened). However, I think you have to close the application while playing sound.
However, there might be an issue with this, because background audio is meant for apps that actually keep running a track/stream in the background. I could see how Apple might reject your app for using their API in an unintended way. So this is the problem with the playing silence trick.
Also, another problem could be that if the user goes out of your app, then starts playing their music through Music or any other music app (Spotify, a radio app etc.) that has access to background audio, your application's audio permissions will be disabled (your app won't be able to play sound anymore through the audio framework, because another app has taken control of the background audio).
An option I would recommend: throw a local notification with your own sound when the user changes location:
UILocalNotification *localNotif = [[UILocalNotification alloc] init];
localNotif.soundName = #"your-sound-file-name";