代码基本很固定，做个笔记，留着以后需要。

• 生成条形码

/**
 *  生成条形码
 *
 *  @return 生成条形码的UIImage对象
 */
+ (UIImage *)resizeCodeWithString:(NSString *)text BCSize:(CGSize)size
{
    CIImage *image = [self generateBarCodeImage:text];
    
    return [self resizeCodeImage:image withSize:size];
}

+ (CIImage *)generateBarCodeImage:(NSString *)source
{
    // iOS 8.0以上的系统才支持条形码的生成，iOS8.0以下使用第三方控件生成
    if ([[UIDevice currentDevice].systemVersion floatValue] >= 8.0) {
        // 注意生成条形码的编码方式
        NSData *data = [source dataUsingEncoding: NSASCIIStringEncoding];
        CIFilter *filter = [CIFilter filterWithName:@"CICode128BarcodeGenerator"];
        [filter setValue:data forKey:@"inputMessage"];
        // 设置生成的条形码的上，下，左，右的margins的值
        [filter setValue:[NSNumber numberWithInteger:0] forKey:@"inputQuietSpace"];
        return filter.outputImage;
    }else{
        return nil;
    }
}
+ (UIImage *)resizeCodeImage:(CIImage *)image withSize:(CGSize)size
{
    if (image) {
        CGRect extent = CGRectIntegral(image.extent);
        CGFloat scaleWidth = size.width/CGRectGetWidth(extent);
        CGFloat scaleHeight = size.height/CGRectGetHeight(extent);
        size_t width = CGRectGetWidth(extent) * scaleWidth;
        size_t height = CGRectGetHeight(extent) * scaleHeight;
        CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceGray();
        CGContextRef contentRef = CGBitmapContextCreate(nil, width, height, 8, 0, colorSpaceRef, (CGBitmapInfo)kCGImageAlphaNone);
        CIContext *context = [CIContext contextWithOptions:nil];
        CGImageRef imageRef = [context createCGImage:image fromRect:extent];
        CGContextSetInterpolationQuality(contentRef, kCGInterpolationNone);
        CGContextScaleCTM(contentRef, scaleWidth, scaleHeight);
        CGContextDrawImage(contentRef, extent, imageRef);
        CGImageRef imageRefResized = CGBitmapContextCreateImage(contentRef);
        UIImage *barImage = [UIImage imageWithCGImage:imageRefResized];

        //Core Foundation 框架下内存泄露问题。
        CGContextRelease(contentRef);
        CGColorSpaceRelease(colorSpaceRef);
        CGImageRelease(imageRef);
        CGImageRelease(imageRefResized);
        return barImage;
    }else{
        return nil;
    }
}

• 生成二维码

+ (UIImage*)createQRWithString:(NSString*)text QRSize:(CGSize)size;
{
    
    NSData *stringData = [text dataUsingEncoding: NSUTF8StringEncoding];
    //生成
    CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    [qrFilter setValue:stringData forKey:@"inputMessage"];
    [qrFilter setValue:@"H" forKey:@"inputCorrectionLevel"];
    
     //上色
    CIFilter *colorFilter = [CIFilter filterWithName:@"CIFalseColor"
                                       keysAndValues:
                             @"inputImage",qrFilter.outputImage,
                             @"inputColor0",[CIColor colorWithCGColor:[UIColor blackColor].CGColor],
                             @"inputColor1",[CIColor colorWithCGColor:[UIColor whiteColor].CGColor],
                             nil];
    
    CIImage *qrImage = colorFilter.outputImage;
    
    //绘制
    CGImageRef cgImage = [[CIContext contextWithOptions:nil] createCGImage:qrImage fromRect:qrImage.extent];
    UIGraphicsBeginImageContext(size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetInterpolationQuality(context, kCGInterpolationNone);
    CGContextScaleCTM(context, 1.0, -1.0);
    CGContextDrawImage(context, CGContextGetClipBoundingBox(context), cgImage);
    UIImage *codeImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    CGImageRelease(cgImage);
    
    return codeImage;
}

最后

附上扫描的三方库: LBXScan