在实现语音转文本时出现此错误：
由于未捕获的异常“com.apple.coreaudio.avfaudio”而终止应用程序，原因：“所需条件为假：_recordingTap == nil”
和：
错误：[0x1b2df5c40] >avae> AVAudioNode.mm:565：CreateRecordingTap：所需条件为假：_recordingTap == nil
这是我的视图控制器的代码：
public class ViewController: UIViewController, SFSpeechRecognizerDelegate {
// MARK: Properties
private let speechRecognizer = SFSpeechRecognizer(locale: Locale(identifier: "en-US"))!
private var recognitionRequest: SFSpeechAudioBufferRecognitionRequest?
private var recognitionTask: SFSpeechRecognitionTask?
private let audioEngine = AVAudioEngine()
@IBOutlet var textView : UITextView!
@IBOutlet var recordButton : UIButton!
// MARK: UIViewController
public override func viewDidLoad() {
super.viewDidLoad()
// Disable the record buttons until authorization has been granted.
recordButton.isEnabled = false
}
override public func viewDidAppear(_ animated: Bool) {
speechRecognizer.delegate = self
SFSpeechRecognizer.requestAuthorization { authStatus in
/*
The callback may not be called on the main thread. Add an
operation to the main queue to update the record button's state.
*/
OperationQueue.main.addOperation {
switch authStatus {
case .authorized:
self.recordButton.isEnabled = true
case .denied:
self.recordButton.isEnabled = false
self.recordButton.setTitle("User denied access to speech recognition", for: .disabled)
case .restricted:
self.recordButton.isEnabled = false
self.recordButton.setTitle("Speech recognition restricted on this device", for: .disabled)
case .notDetermined:
self.recordButton.isEnabled = false
self.recordButton.setTitle("Speech recognition not yet authorized", for: .disabled)
}
}
}
}
private func startRecording() throws {
// Cancel the previous task if it's running.
if let recognitionTask = recognitionTask {
recognitionTask.cancel()
self.recognitionTask = nil
}
let audioSession = AVAudioSession.sharedInstance()
try audioSession.setCategory(AVAudioSessionCategoryRecord)
try audioSession.setMode(AVAudioSessionModeMeasurement)
try audioSession.setActive(true, with: .notifyOthersOnDeactivation)
recognitionRequest = SFSpeechAudioBufferRecognitionRequest()
guard let inputNode = audioEngine.inputNode else { fatalError("Audio engine has no input node") }
guard let recognitionRequest = recognitionRequest else { fatalError("Unable to created a SFSpeechAudioBufferRecognitionRequest object") }
// Configure request so that results are returned before audio recording is finished
recognitionRequest.shouldReportPartialResults = true
// A recognition task represents a speech recognition session.
// We keep a reference to the task so that it can be cancelled.
recognitionTask = speechRecognizer.recognitionTask(with: recognitionRequest) { result, error in
var isFinal = false
if let result = result {
self.textView.text = result.bestTranscription.formattedString
isFinal = result.isFinal
}
if error != nil || isFinal {
self.audioEngine.stop()
inputNode.removeTap(onBus: 0)
self.recognitionRequest = nil
self.recognitionTask = nil
self.recordButton.isEnabled = true
self.recordButton.setTitle("Start Recording", for: [])
}
}
let recordingFormat = inputNode.outputFormat(forBus: 0)
inputNode.installTap(onBus: 0, bufferSize: 1024, format: recordingFormat) { (buffer: AVAudioPCMBuffer, when: AVAudioTime) in
self.recognitionRequest?.append(buffer)
}
audioEngine.prepare()
try audioEngine.start()
textView.text = "(Go ahead, I'm listening)"
}
// MARK: SFSpeechRecognizerDelegate
public func speechRecognizer(_ speechRecognizer: SFSpeechRecognizer, availabilityDidChange available: Bool) {
if available {
recordButton.isEnabled = true
recordButton.setTitle("Start Recording", for: [])
} else {
recordButton.isEnabled = false
recordButton.setTitle("Recognition not available", for: .disabled)
}
}
// MARK: Interface Builder actions
@IBAction func recordButtonTapped() {
if audioEngine.isRunning {
audioEngine.stop()
recognitionRequest?.endAudio()
recordButton.isEnabled = false
recordButton.setTitle("Stopping", for: .disabled)
} else {
try! startRecording()
recordButton.setTitle("Stop recording", for: [])
}
}
}