Routing iPhone Audio Sound

Question

I have an app which does listen and play sound at the same time. By default, the sound output goes through the earphone. So I use the following code to route it through the speaker:

UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;
AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute, sizeof(audioRouteOverride), &audioRouteOverride);

This works fine. But now, I'd like to route the sound through the headphones when headphones or external speakers are attached. How would I achieve that?

Also ideally all other sound (i.e. music etc.) should mute when the app launches.

Thanks!

Answer 1

To do this you have to add property listener when you setup audio session:

AudioSessionAddPropertyListener(kAudioSessionProperty_AudioRouteChange, audioSessionPropertyListener, nil);

Where

void audioSessionPropertyListener(void* inClientData, AudioSessionPropertyID inID,
                                          UInt32 inDataSize, const void* inData) {
          UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker;

          if (!isHeadsetPluggedIn()) 
            AudioSessionSetProperty (kAudioSessionProperty_OverrideAudioRoute,sizeof (audioRouteOverride),&audioRouteOverride);
        }

BOOL isHeadsetPluggedIn() {
  UInt32 routeSize = sizeof (CFStringRef);
  CFStringRef route;

  OSStatus error = AudioSessionGetProperty (kAudioSessionProperty_AudioRoute,
                                            &routeSize,
                                            &route
                                            );



     if (!error && (route != NULL) && ([(NSString*)route rangeOfString:@"Head"].location != NSNotFound)) {
        NSLog(@"HeadsetPluggedIn");
        return YES;
      }
      NSLog(@"Headset_NOT_PluggedIn");
      return NO;
    }

So when headphones are plugged in or out you get a notification and change audio output direction.