Recognize Speech To Text Swift

问题

Is it possible to recognize speech and then convert it into text with custom keyboard. Like by default message app in iphone.

Screen Shot

1. Default recognize speech in iphone keyboard.

2. Speech to text

Any help would be greatly appreciated.

Thanks in advance.

回答1:

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.

来源：https://stackoverflow.com/questions/53849787/recognize-speech-to-text-swift