ios微信语音播放之切换听筒和扬声器

[[UIDevice currentDevice] setProximityMonitoringEnabled:YES]; //建议在播放之前设置yes，播放结束设置NO，这个功能是开启红外感应

//添加监听
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(sensorStateChange:)
name:@"UIDeviceProximityStateDidChangeNotification"
object:nil];

//处理监听触发事件
-(void)sensorStateChange:(NSNotificationCenter *)notification;
{
//如果此时手机靠近面部放在耳朵旁，那么声音将通过听筒输出，并将屏幕变暗（省电啊）
if ([[UIDevice currentDevice] proximityState] == YES)
{
NSLog(@"Device is close to user");
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord error:nil];

}
else
{
NSLog(@"Device is not close to user");
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:nil];
}
}