AVSpeechUtterance的最大音量非常安静，速度非常快

Question

我在我的应用程序中添加语音提示，并在iOS 7中测试AVSpeechUtterance，但默认的语音速率真的很快。最低语音速率更容易理解。但是音量的最大值1太安静了！我在我的iPhone 4上测试了它，音量一直开到最大。一定是出了什么问题，否则这怎么会有用呢？

AVSpeechSynthesizer *synthesizer = [[AVSpeechSynthesizer alloc]init];
            NSString *mystring = [NSString stringWithFormat:@"Talk String Here %@",myObject.name];
            AVSpeechUtterance *utterance = [AVSpeechUtterance speechUtteranceWithString:mystring];
            [utterance setRate:AVSpeechUtteranceMinimumSpeechRate];
            [utterance setVolume:1];
            [synthesizer speakUtterance:utterance];

Answer 1

这对我很有效( Swift 3.0 )

let audioSession = AVAudioSession.sharedInstance()  
do {
  try audioSession.setCategory(AVAudioSessionCategoryPlayAndRecord, with: AVAudioSessionCategoryOptions.defaultToSpeaker)  
} catch {   
  print("audioSession properties weren't set because of an error.")   
}

Answer 2

@tmr的帖子here为我解决了这个问题：

[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord  
                       withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker
                                       error:nil];

Answer 3

对于Swift 5，你可以尝试这个(在合成器初始化之前添加它)：

        let audioSession = AVAudioSession.sharedInstance()
        try? audioSession.setCategory(AVAudioSession.Category.playAndRecord, mode: AVAudioSession.Mode.default, options: AVAudioSession.CategoryOptions.defaultToSpeaker)
        try? audioSession.setMode(AVAudioSession.Mode.spokenAudio)