iOS 基于Vision.framework从图片中提取文字

基于Vision.framework从图片中提取文字 苹果在iOS 11中引入的Vision框架为OCR提供了基础能力，其核心组件VNRecognizeTextRequest可实现高效文字检测与识别。结合VisionKit中的DocumentCameraViewController，开发者可快速构建扫描界面，支持自动裁剪、透视校正等预处理功能。

技术优势：

硬件加速 ：利用神经网络引擎（Neural Engine）实现低功耗、高帧率识别
隐私保护：所有计算在设备端完成，无需上传至云端
系统级优化：与iOS相机、相册系统深度集成

objectivec 复制代码

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

NS_ASSUME_NONNULL_BEGIN

API_AVAILABLE(ios(11.0))
typedef void(^SBVisionTextCallBack)(NSError *error, NSArray<__kindof VNObservation*>* results);


API_AVAILABLE(ios(11.0))

@interface SBVisionText : NSObject

@property (nonatomic,copy)SBVisionTextCallBack resultBlock;

+ (void)sb_vision_text_image:(UIImage *)img result:(SBVisionTextCallBack) resultBlock;

@end


#import "SBVisionText.h"

@implementation SBVisionText

+ (void)sb_vision_text_image:(UIImage *)img result:(SBVisionTextCallBack) resultBlock{

    if (@available(iOS 13.0, *)) {

        VNRecognizeTextRequest *textRequest = [[VNRecognizeTextRequest alloc] initWithCompletionHandler:^(VNRequest * _Nonnull request, NSError * _Nullable error){

            NSArray *observations = request.results;

            //        [self textRectangles:observations image:image complete:complete];

            NSLog(@"sb_vision_text_image:%@",observations);

            if (resultBlock) {
                resultBlock(error,request.results);
            }
        }];
        
        textRequest.recognitionLevel = VNRequestTextRecognitionLevelAccurate;
        textRequest.usesLanguageCorrection = NO;
        textRequest.recognitionLanguages = @[@"zh-Hans", @"en-US"];

        // 转换CIImage
        CIImage *convertImage = [[CIImage alloc]initWithImage:img];

        // 创建处理requestHandler

        VNImageRequestHandler *detectRequestHandler = [[VNImageRequestHandler alloc]initWithCIImage:convertImage options:@{}];

        // 发送识别请求
        [detectRequestHandler performRequests:@[textRequest] error:nil];

    } else {
        // Fallback on earlier versions
        NSLog(@"Fallback on earlier versions");
    }
}

@end

方法调用

swift 复制代码

#import "SBVisionTextViewController.h"
#import "SBVisionText.h"


@implementation SBVisionTextViewController
- (void)viewDidLoad {
    [super viewDidLoad];
}

- (IBAction)getText:(UIButton *)sender {
    [self getTextFormImage:[UIImage imageNamed:@"1681888102373.jpg"]];
}

-(void)getTextFormImage:(UIImage *)img{
    if (@available(iOS 11.0, *)) {
        [SBVisionText sb_vision_text_image:img result:^(NSError * _Nonnull error, NSArray<__kindof VNObservation *> * _Nonnull results) {

            if (@available(iOS 13.0, *)) {
                for (VNRecognizedTextObservation *observation in results) {
                    NSLog(@"%@", [observation topCandidates:1].firstObject.string);
                }
            } else {
                NSLog(@"Fallback on earlier versions");
            }
        }];

    } else {
        NSLog(@"Fallback on earlier versions");
    }
    return;
}

@end