iOS 音频播放时听筒及扬声器切换

- (IBAction)playPause:(UIButton *)sender
{
//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];

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

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

[self handleNotification:YES];
[myPlayer play];
}

- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag
{
NSLog(@"播放结束");
[self handleNotification:NO];
[myPlayer release];
}

#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];
}
}