iOS下语音播放之切换听筒和扬声器的方法解决方案

原理：开启红外感应，根据红外感应气话播放听筒还是扬声器。

[[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];
}
}


//初始化播放器的时候如下设置
UInt32 sessionCategory = kAudioSessionCategory_MediaPlayback;
AudioSessionSetProperty(kAudioSessionProperty_AudioCategory,
sizeof(sessionCategory),
&sessionCategory); 

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

AVAudioSession *audioSession = [AVAudioSession sharedInstance];
//默认情况下扬声器播放
[audioSession setCategory:AVAudioSessionCategoryPlayback error:nil];
[audioSession setActive:YES error:nil];