Recognize Speech To Text Swift

I have following code which are used in my sample application to convert speech-to-text.

import UIKit import Speech import AVKit class ViewController: UIViewController { //------------------------------------------------------------------------------ // MARK:- // MARK:- Outlets //------------------------------------------------------------------------------ @IBOutlet weak var btnStart : UIButton! @IBOutlet weak var lblText : UILabel! //------------------------------------------------------------------------------ // MARK:- // MARK:- Variables //------------------------------------------------------------------------------ let speechRecognizer = SFSpeechRecognizer(locale: Locale(identifier: "en-US")) var recognitionRequest : SFSpeechAudioBufferRecognitionRequest? var recognitionTask : SFSpeechRecognitionTask? let audioEngine = AVAudioEngine() //------------------------------------------------------------------------------ // MARK:- // MARK:- Action Methods //------------------------------------------------------------------------------ @IBAction func btnStartSpeechToText(_ sender: UIButton) { if audioEngine.isRunning { self.audioEngine.stop() self.recognitionRequest?.endAudio() self.btnStart.isEnabled = false self.btnStart.setTitle("Start Recording", for: .normal) } else { self.startRecording() self.btnStart.setTitle("Stop Recording", for: .normal) } } //------------------------------------------------------------------------------ // MARK:- // MARK:- Custom Methods //------------------------------------------------------------------------------ func setupSpeech() { self.btnStart.isEnabled = false self.speechRecognizer?.delegate = self SFSpeechRecognizer.requestAuthorization { (authStatus) in var isButtonEnabled = false switch authStatus { case .authorized: isButtonEnabled = true case .denied: isButtonEnabled = false print("User denied access to speech recognition") case .restricted: isButtonEnabled = false print("Speech recognition restricted on this device") case .notDetermined: isButtonEnabled = false print("Speech recognition not yet authorized") } OperationQueue.main.addOperation() { self.btnStart.isEnabled = isButtonEnabled } } } //------------------------------------------------------------------------------ func startRecording() { // Clear all previous session data and cancel task if recognitionTask != nil { recognitionTask?.cancel() recognitionTask = nil } // Create instance of audio session to record voice let audioSession = AVAudioSession.sharedInstance() do { try audioSession.setCategory(AVAudioSession.Category.record, mode: AVAudioSession.Mode.measurement, options: AVAudioSession.CategoryOptions.defaultToSpeaker) try audioSession.setActive(true, options: .notifyOthersOnDeactivation) } catch { print("audioSession properties weren't set because of an error.") } self.recognitionRequest = SFSpeechAudioBufferRecognitionRequest() let inputNode = audioEngine.inputNode guard let recognitionRequest = recognitionRequest else { fatalError("Unable to create an SFSpeechAudioBufferRecognitionRequest object") } recognitionRequest.shouldReportPartialResults = true self.recognitionTask = speechRecognizer?.recognitionTask(with: recognitionRequest, resultHandler: { (result, error) in var isFinal = false if result != nil { self.lblText.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.btnStart.isEnabled = true } }) let recordingFormat = inputNode.outputFormat(forBus: 0) inputNode.installTap(onBus: 0, bufferSize: 1024, format: recordingFormat) { (buffer, when) in self.recognitionRequest?.append(buffer) } self.audioEngine.prepare() do { try self.audioEngine.start() } catch { print("audioEngine couldn't start because of an error.") } self.lblText.text = "Say something, I'm listening!" } //------------------------------------------------------------------------------ // MARK:- // MARK:- View Life Cycle Methods //------------------------------------------------------------------------------ override func viewDidLoad() { super.viewDidLoad() self.setupSpeech() } } //------------------------------------------------------------------------------ // MARK:- // MARK:- SFSpeechRecognizerDelegate Methods //------------------------------------------------------------------------------ extension ViewController: SFSpeechRecognizerDelegate { func speechRecognizer(_ speechRecognizer: SFSpeechRecognizer, availabilityDidChange available: Bool) { if available { self.btnStart.isEnabled = true } else { self.btnStart.isEnabled = false } } } 

I have attached following screenshot for above ViewController's UI.