如何收听该属性？

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. 

那么，如果我想收到有关 kAudioSessionProperty_AudioInputAvailable 的通知，我该怎么做？

Answer 1

你这样设置监听器：

AudioSessionAddPropertyListener(kAudioSessionProperty_AudioInputAvailable, myCallback, NULL);

你必须定义一个回调函数，只要值改变就会被调用：

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