iOS__播放mp3文件根据光线传感器设置外置或者听筒播放

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];

NSError *playerError;
  //    self.player = [[AVAudioPlayer alloc] initWithContentsOfURL:[NSURL URLWithString:[VoiceRecorderBaseVC getPathByFileName:recordedFile ofType:@"aac"]] error:&playerError];
self.player.meteringEnabled = YES;


if (self.player == nil)
{
    NSLog(@"ERror creating player: %@", [playerError description]);
}

[self handleNotification:YES];
self.player.delegate = self;
self.player.volume = 1;
[self.player play];

pragma mark - 监听听筒or扬声器

- (void) handleNotification:(BOOL)state
{
[[UIDevice currentDevice] setProximityMonitoringEnabled:state]; //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

if(state)//添加监听
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(sensorStateChange:) name:@"UIDeviceProximityStateDidChangeNotification"
                                               object:nil];
else//移除监听
    [[NSNotificationCenter defaultCenter] removeObserver:self 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];
    }
}