How to listen to that property?

Question

@constant       kAudioSessionProperty_AudioInputAvailable 
                    A UInt32 with a value other than zero when audio input is available.
                    Use this property, rather than the device model, to determine if audio input is available.
                    A listener will notify you when audio input becomes available.  For instance, when a headset is attached
                    to the second generation iPod Touch, audio input becomes available via the wired microphone. 

So, if I wanted to get notified about kAudioSessionProperty_AudioInputAvailable, how would I do that?

Answer 1

You set up the listener like this:

AudioSessionAddPropertyListener(kAudioSessionProperty_AudioInputAvailable, myCallback, NULL);

You have to define a callback function which gets called whenever the value changes:

void myCallback(void* inClientData, AudioSessionPropertyID inID, UInt32 inDataSize, const void* inData)
{
    printf("value changed\n");
}