func playAudio(audioString:String){

    do {
        
        let se = AVAudioSession.sharedInstance()
        try se.setActive(true, options: .notifyOthersOnDeactivation)
        try se.setCategory(.playback, options: .allowAirPlay)
        
    } catch  {
        
    }

    
    speaker = AVSpeechSynthesizer.init()
    let detailTerance = AVSpeechUtterance.init(string: audioString)
    ///語速
    detailTerance.rate = 0.5
    detailTerance.pitchMultiplier = 1//音高
    detailTerance.volume = 1
    
    detailTerance.preUtteranceDelay = 1
    
    detailTerance.postUtteranceDelay = 1
    
    
    let voice = AVSpeechSynthesisVoice.init(language: "zh-CN")
    
    
    detailTerance.voice = voice
    
    
    speaker.speak(detailTerance)
    
    
}