如何通过 Objective-C 中的语音框架实现语音转文本？

我想使用 iOS 语音框架在我的 Objective-C 应用程序中进行语音识别。

我找到了一些 Swift 示例，但在 Objective-C 中找不到任何内容。

是否可以从 Objective-C 访问这个框架？如果是这样，怎么办？

在花了足够的时间寻找 Objective-C 示例之后——即使是在 Apple 文档中——我也找不到任何像样的东西，所以我自己解决了。

头文件（.h）

/*!
 * Import the Speech framework, assign the Delegate and declare variables
 */

#import <Speech/Speech.h>

@interface ViewController : UIViewController <SFSpeechRecognizerDelegate> {
    SFSpeechRecognizer *speechRecognizer;
    SFSpeechAudioBufferRecognitionRequest *recognitionRequest;
    SFSpeechRecognitionTask *recognitionTask;
    AVAudioEngine *audioEngine;
}

方法文件 (.m)

- (void)viewDidLoad {
    [super viewDidLoad];

    // Initialize the Speech Recognizer with the locale, couldn't find a list of locales
    // but I assume it's standard UTF-8 https://wiki.archlinux.org/index.php/locale
    speechRecognizer = [[SFSpeechRecognizer alloc] initWithLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"]];

    // Set speech recognizer delegate
    speechRecognizer.delegate = self;

    // Request the authorization to make sure the user is asked for permission so you can
    // get an authorized response, also remember to change the .plist file, check the repo's
    // readme file or this project's info.plist
    [SFSpeechRecognizer requestAuthorization:^(SFSpeechRecognizerAuthorizationStatus status) {
        switch (status) {
            case SFSpeechRecognizerAuthorizationStatusAuthorized:
                NSLog(@"Authorized");
                break;
            case SFSpeechRecognizerAuthorizationStatusDenied:
                NSLog(@"Denied");
                break;
            case SFSpeechRecognizerAuthorizationStatusNotDetermined:
                NSLog(@"Not Determined");
                break;
            case SFSpeechRecognizerAuthorizationStatusRestricted:
                NSLog(@"Restricted");
                break;
            default:
                break;
        }
    }];

}

/*!
 * @brief Starts listening and recognizing user input through the 
 * phone's microphone
 */

- (void)startListening {

    // Initialize the AVAudioEngine
    audioEngine = [[AVAudioEngine alloc] init];

    // Make sure there's not a recognition task already running
    if (recognitionTask) {
        [recognitionTask cancel];
        recognitionTask = nil;
    }

    // Starts an AVAudio Session
    NSError *error;
    AVAudioSession *audioSession = [AVAudioSession sharedInstance];
    [audioSession setCategory:AVAudioSessionCategoryRecord error:&error];
    [audioSession setActive:YES withOptions:AVAudioSessionSetActiveOptionNotifyOthersOnDeactivation error:&error];

    // Starts a recognition process, in the block it logs the input or stops the audio
    // process if there's an error.
    recognitionRequest = [[SFSpeechAudioBufferRecognitionRequest alloc] init];
    AVAudioInputNode *inputNode = audioEngine.inputNode;
    recognitionRequest.shouldReportPartialResults = YES;
    recognitionTask = [speechRecognizer recognitionTaskWithRequest:recognitionRequest resultHandler:^(SFSpeechRecognitionResult * _Nullable result, NSError * _Nullable error) {
        BOOL isFinal = NO;
        if (result) {
            // Whatever you say in the microphone after pressing the button should be being logged
            // in the console.
            NSLog(@"RESULT:%@",result.bestTranscription.formattedString);
            isFinal = !result.isFinal;
        }
        if (error) {
            [audioEngine stop];
            [inputNode removeTapOnBus:0];
            recognitionRequest = nil;
            recognitionTask = nil;
        }
    }];

    // Sets the recording format
    AVAudioFormat *recordingFormat = [inputNode outputFormatForBus:0];
    [inputNode installTapOnBus:0 bufferSize:1024 format:recordingFormat block:^(AVAudioPCMBuffer * _Nonnull buffer, AVAudioTime * _Nonnull when) {
        [recognitionRequest appendAudioPCMBuffer:buffer];
    }];

    // Starts the audio engine, i.e. it starts listening.
    [audioEngine prepare];
    [audioEngine startAndReturnError:&error];
    NSLog(@"Say Something, I'm listening"); 
}

- (IBAction)microPhoneTapped:(id)sender {
    if (audioEngine.isRunning) {
        [audioEngine stop];
        [recognitionRequest endAudio];
    } else {
        [self startListening];
    }
}

现在，添加委托SFSpeechRecognizerDelegate检查语音识别器是否可用。

#pragma mark - SFSpeechRecognizerDelegate Delegate Methods

- (void)speechRecognizer:(SFSpeechRecognizer *)speechRecognizer availabilityDidChange:(BOOL)available {
    NSLog(@"Availability:%d",available);
}

说明和注意事项

记得修改.plist文件以获得用户语音识别和使用麦克风的授权，当然<String>值必须根据您的需要进行定制，您可以通过创建和修改中的值来做到这一点Property List或右键单击.plist文件和Open As -> Source Code并将以下行粘贴到</dict> tag.

<key>NSMicrophoneUsageDescription</key>  <string>This app uses your microphone to record what you say, so watch what you say!</string>

<key>NSSpeechRecognitionUsageDescription</key>  <string>This app uses Speech recognition to transform your spoken words into text and then analyze the, so watch what you say!.</string>

另请记住，为了能够将语音框架导入到项目中，您需要拥有 iOS 10.0+。

要运行并测试它，您只需要一个非常基本的 UI，只需创建一个 UIButton 并分配microPhoneTapped对其进行操作，当按下时，应用程序应该开始监听并将通过麦克风听到的所有内容记录到控制台（在示例代码中）NSLog是唯一接收文本的东西）。再次按下时应停止录音。

我创建了一个Github 仓库附带示例项目，尽情享受吧！