问不能重复使用SFSpeechAudioBufferRecognitionRequest。

EN

private func recordAndRecognizeSpeech()
    {
        let node = audioEngine.inputNode
        let recordingFormat = node.outputFormat(forBus: 0)
        node.installTap(onBus: 0, bufferSize: 1024, format: recordingFormat) { buffer, _ in
            self.request.append(buffer)
        }

        audioEngine.prepare()
        do {
            try audioEngine.start()
        }
        catch {
            self.sendAlert(message: "There has been an audio engine error.")
            return print (error)
        }

        guard let myRecognizer = SFSpeechRecognizer() else
        {
            self.sendAlert(message: "Speech recognition is not supported for your current locale.")
            return
        }

        if !myRecognizer.isAvailable
        {
            self.sendAlert(message: "Speech recognition is not currently available. Check back at a later time.")
            return
        }

        recognitionTask = speechRecognizer?.recognitionTask(with: request, resultHandler:
        { result, error in
            if result != nil
            {
                if let result = result
                {
                    let bestString = result.bestTranscription.formattedString
                    self.detectedTextLabel.text = bestString
                }

                else if let error = error
                {
                    self.sendAlert(message: "There has been a speech recognition error.")
                    print(error)
                }
            }
        })
    }

    /// This button is the toggle for Starting and Stopping the Speech Recognition function
    @objc func didTapSpeechButton()
    {
        if isRecording == true {
            print("--> Stop Recording.")
            request.endAudio()  // Mark end of recording
            audioEngine.stop()
            let node = audioEngine.inputNode
            node.removeTap(onBus: 0)
            recognitionTask?.cancel()
            isRecording = false
            speechButton.backgroundColor = UIColor.red
        } else {
            print("--> Start Recording.")
            self.recordAndRecognizeSpeech()
            isRecording = true
            speechButton.backgroundColor = UIColor.gray
        }
    }