问SFSpeechRecognizer失败，出现错误Domain=kAFAssistantErrorDomain Code=1700 on Ipad

EN

func requestTranscribePermissions() {
    SFSpeechRecognizer.requestAuthorization { [unowned self] authStatus in
        DispatchQueue.main.async {
            if authStatus == .authorized {
                print("Good to go!")
            } else {
                print("Transcription permission was declined.")
            }
        }
    }
}


func convertAudioToText() {
            if let file = audio {
            print(file)

            let recognizer = SFSpeechRecognizer(locale: Locale(identifier: "en-US"))
            let request = SFSpeechURLRecognitionRequest(url: file)

                request.shouldReportPartialResults = false

                if (recognizer?.isAvailable)! {

                    recognizer?.recognitionTask(with: request) { result, error in
                        guard error == nil else { print("Error: \(error!)"); return }
                        guard let result = result else { print("No result!"); return }

                        self.text = result.bestTranscription.formattedString
                        self.performSegue(withIdentifier: "Convert", sender: nil)

                        print(result.bestTranscription.formattedString)
                    }
                } else {
                    print("Device doesn't support speech recognition")
                }
        } else {
            let alert = UIAlertController(title: "There's no audio", message: "No audio recorded", preferredStyle: .alert)
            alert.addAction(UIAlertAction(title: NSLocalizedString("OK", comment: "Default action"), style: .default, handler: { _ in
            NSLog("The \"OK\" alert occured.")
            }))
            self.present(alert, animated: true, completion: nil)

        }