IOS自带的OCR识别功能

一、识别身份证

@interface IDCardScanViewController () <AVCaptureMetadataOutputObjectsDelegate>

@property (nonatomic, strong) AVCaptureSession *captureSession;

@end

@implementation IDCardScanViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // 创建视频预览层
    AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
    previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    previewLayer.frame = self.scanView.bounds;
    [self.scanView.layer addSublayer:previewLayer];
    
    // 创建数据输出
    AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
    [self.captureSession addOutput:output];
    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    
    // 设置扫描支持的码类型
    if ([output.availableMetadataObjectTypes containsObject:AVMetadataObjectTypeIDCard]) {
        output.metadataObjectTypes = @[AVMetadataObjectTypeIDCard];
    }
    
    // 启动扫描
    [self.captureSession startRunning];
}

- (AVCaptureSession *)captureSession {
    if (!_captureSession) {
        _captureSession = [[AVCaptureSession alloc] init];
        
        // 配置摄像头输入
        AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
        AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
        [_captureSession addInput:input];
    }
    return _captureSession;
}

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray<__kindof AVMetadataObject *> *)metadataObjects fromConnection:(AVCaptureConnection *)connection {
    for (AVMetadataObject *metadata in metadataObjects) {
        if ([metadata isKindOfClass:[AVMetadataMachineReadableCodeObject class]]) {
            AVMetadataMachineReadableCodeObject *code = (AVMetadataMachineReadableCodeObject *)metadata;
            if ([code.type isEqualToString:AVMetadataObjectTypeIDCard]) {
                NSString *result = code.stringValue;
                
                // 对扫描结果进行处理
                NSLog(@"扫描结果：%@", result);
            }
        }
    }
}

下面的方法需要iOS13以上才能支持

#import <Vision/Vision.h>
#import <VisionKit/VisionKit.h>

@interface ViewController () <VNDocumentCameraViewControllerDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // 在需要的地方调用此方法启动身份证扫描
    [self startDocumentCapture];
}

- (void)startDocumentCapture {
    VNDocumentCameraViewController *documentCameraViewController = [[VNDocumentCameraViewController alloc] init];
    documentCameraViewController.delegate = self;
    [self presentViewController:documentCameraViewController animated:YES completion:nil];
}

#pragma mark - VNDocumentCameraViewControllerDelegate

- (void)documentCameraViewController:(VNDocumentCameraViewController *)controller didFinishWithScan:(VNDocumentCameraScan *)scan {
    // 遍历扫描结果
    for (NSUInteger pageIndex = 0; pageIndex < scan.pageCount; pageIndex++) {
        VNPage *page = [scan pageAtIndex:pageIndex];
        
        // 检查扫描结果是否为身份证
        if ([self isIdentityCard:page]) {
            // 获取身份证号码和姓名
            NSString *number = [self identityCardNumberFromPage:page];
            NSString *name = [self identityCardNameFromPage:page];
            
            NSLog(@"身份证号码：%@", number);
            NSLog(@"姓名：%@", name);
            
            // 在这里进行身份证识别后的处理
        }
    }
    
    // 关闭扫描视图控制器
    [controller dismissViewControllerAnimated:YES completion:nil];
}

- (void)documentCameraViewControllerDidCancel:(VNDocumentCameraViewController *)controller {
    // 用户取消了扫描，关闭扫描视图控制器
    [controller dismissViewControllerAnimated:YES completion:nil];
}

- (void)documentCameraViewController:(VNDocumentCameraViewController *)controller didFailWithError:(NSError *)error {
    // 扫描失败，处理错误信息
    NSLog(@"扫描身份证发生错误：%@", error);
    [controller dismissViewControllerAnimated:YES completion:nil];
}

#pragma mark - Helper Methods

- (BOOL)isIdentityCard:(VNPage *)page {
    // 获取页面文本内容
    NSString *text = page.recognizedText.string;
    
    // 判断是否包含“公民身份号码”和“姓名”关键字
    if ([text containsString:@"公民身份号码"] && [text containsString:@"姓名"]) {
        return YES;
    }
    
    return NO;
}

- (NSString *)identityCardNumberFromPage:(VNPage *)page {
    // 获取页面文本内容
    NSString *text = page.recognizedText.string;
    
    // 查找身份证号码
    NSRange range = [text rangeOfString:@"公民身份号码"];
    if (range.location != NSNotFound) {
        NSString *number = [text substringFromIndex:range.location + range.length];
        number = [number stringByReplacingOccurrencesOfString:@" " withString:@""];
        
        return number;
    }
    
    return nil;
}

- (NSString *)identityCardNameFromPage:(VNPage *)page {
    // 获取页面文本内容
    NSString *text = page.recognizedText.string;
    
    // 查找姓名
    NSRange range = [text rangeOfString:@"姓名"];
    if (range.location != NSNotFound) {
        NSString *name = [text substringFromIndex:range.location + range.length];
        name = [name stringByReplacingOccurrencesOfString:@" " withString:@""];
        
        return name;
    }
    
    return nil;
}

@end

二、识别图片上的文字

#import <Vision/Vision.h>

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    UIImage *image = [UIImage imageNamed:@"test_image.jpg"];
    [self recognizeTextInImage:image];
}

- (void)recognizeTextInImage:(UIImage *)image {
    // 创建VNImageRequestHandler对象
    VNImageRequestHandler *requestHandler = [[VNImageRequestHandler alloc] initWithCGImage:image.CGImage options:@{}];
    
    // 创建VNRecognizeTextRequest对象
    VNRecognizeTextRequest *textRequest = [[VNRecognizeTextRequest alloc] initWithCompletionHandler:^(VNRequest * _Nonnull request, NSError * _Nullable error) {
        // 处理识别结果
        if (error == nil) {
            NSArray *results = request.results;
            NSMutableString *recognizedText = [NSMutableString string];
            for (VNRecognizedTextObservation *observation in results) {
                for (VNRecognizedText *text in observation.topCandidates(1)) {
                    [recognizedText appendString:text.string];
                    [recognizedText appendString:@"\n"];
                }
            }
            
            NSLog(@"识别结果：%@", recognizedText);
            
            // 在这里进行识别后的处理
        } else {
            NSLog(@"识别出错：%@", error);
        }
    }];
    
    // 设置识别方式和语种
    textRequest.recognitionLevel = VNRequestTextRecognitionLevelAccurate;
    textRequest.usesLanguageCorrection = YES;
    
    // 发送识别请求
    NSError *requestError = nil;
    [requestHandler performRequests:@[textRequest] error:&requestError];
    if (requestError != nil) {
        NSLog(@"发送识别请求出错：%@", requestError);
    }
}

@end