Iphone 怎么听那个属性？

因此，如果我想得到关于kAudioSessionProperty\u AudioInputAvailable的通知，我该如何做？

您可以这样设置侦听器：

@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. 

您必须定义一个回调函数，该函数在值更改时被调用：

AudioSessionAddPropertyListener(kAudioSessionProperty_AudioInputAvailable, myCallback, NULL);

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