iOS下微信语音播放之切换听筒和扬声器的方法

setProximityMonitoringEnabled
不知道是应该叫红外感应还是应该叫什么，就是打电话的时候会自动黑屏的那个API,原来没注意过。

 UIDevice *_curDevice = [UIDevice currentDevice];
[_curDevice setProximityMonitoringEnabled:YES];
NSNotificationCenter *_defaultCenter = [NSNotificationCenter defaultCenter];
[_defaultCenter addObserverForName:UIDeviceProximityStateDidChangeNotification
                          object:nil
                           queue:[NSOperationQueue mainQueue]
                      usingBlock:^(NSNotification *note) {
                        if (_curDevice.proximityState == YES) {
                          NSLog(@"怕是黑屏了吧");
                        }
                        else {
                          NSLog(@"屏幕应该亮了");
                        }
                      }];

 [[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 = 
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];