与AVSpeechUtterance混合使用AVAudioSession

Question

我有一个问题，我想让iPod在后台播放音乐，在我的应用程序中，我想让AVSpeechUtterance降低iPod的音量，播放一串文本，然后我想让iPod继续播放。我尝试过几种方法，但从未让AVAudioSession和AVSpeechUtterance很好地协同工作。我可以让iPod停止，暂停片刻，然后重新开始播放。我可以看到我的字符串被传递给AVSpeechUtterance，但它没有优先于扬声器播放。下面是我的代码：

视图did加载：

   - (void)viewDidLoad
   {
            //set the audio session for my app to play from the TTS library
            NSError *error;
            audioSession = [AVAudioSession sharedInstance];
            [audioSession setCategory:AVAudioSessionCategoryAmbient withOptions:1  error:&error];
            [audioSession setActive:YES error:&error];
            if(error){
                NSLog(@"Audio Error %@", error);
            }

            syn = [[AVSpeechSynthesizer alloc] init];
            syn.delegate = self;

            iPodMusicPlayer = [[MPMusicPlayerController alloc] init];

   }

下面是我的语音函数：

   -(void)speech:(NSString *)string
   {
             if(audioSession.isOtherAudioPlaying){
                 wasPlaying = YES;
                 NSLog(@"Other audio is playing");
                 [iPodMusicPlayer pause];
             }

             AVSpeechUtterance *utterance = [AVSpeechUtterance speechUtteranceWithString:string];
             utterance.rate = 0.3f;
             utterance.volume = 1.0;
             [syn speakUtterance:utterance];

   }

在语音结束后调用的AVSpeechSynthesizer委托方法

   - (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didFinishSpeechUtterance:(AVSpeechUtterance *)utterance
   {
         if(wasPlaying){
            NSLog(@"Start Playing");
            [iPodMusicPlayer play];
            wasPlaying = NO;
         }
   }

我查看了AVAudioSession here上的苹果文档，看起来我已经正确地实现了所有的东西。有人知道我哪里出错了吗？

Answer 1

我只是想让每个人知道，经过一些故障排除后，这就是我能够解决问题的方法。我不确定我是否喜欢这个解决方案，并正在努力改进它。

视图Did加载

    - (void)viewDidLoad
    {
            syn = [[AVSpeechSynthesizer alloc] init];
            syn.delegate = self;

            iPodMusicPlayer = [[MPMusicPlayerController alloc] init];
    }

语音功能

    -(void)speak:(NSString *)string
    {

            audioSession = [AVAudioSession sharedInstance];

            NSError *setCategoryError = nil;
            NSError *activationError = nil;
            BOOL success = [audioSession setCategory:AVAudioSessionCategoryPlayback
                withOptions:AVAudioSessionCategoryOptionMixWithOthers error:&setCategoryError];

            [audioSession setActive:YES error:&activationError];

            if(audioSession.isOtherAudioPlaying){
                wasPlaying = YES;
                NSLog(@"Other audio is playing");
                [iPodMusicPlayer pause];
            }

            NSLog(@"Success %hhd", success);

            AVSpeechUtterance *utterance = [AVSpeechUtterance           speechUtteranceWithString:string];
            utterance.rate = 0.3f;
            utterance.volume = 1.0;
            [syn speakUtterance:utterance];
     }

在语音结束后调用的AVSpeechSynthesizer委托方法

     - (void)speechSynthesizer:(AVSpeechSynthesizer *)synthesizer didFinishSpeechUtterance:(AVSpeechUtterance *)utterance
     {
            if(wasPlaying){
                NSLog(@"Start Playing");
               [iPodMusicPlayer play];
               wasPlaying = NO;
            }
     }