iOS,QRCord(矩阵二维码)

#import <CoreImage/CoreImage.h>

/**
 生成二维码图片

 @param text 文本
 @param size 图片宽度
 @return 二维码图片
 */
-(UIImage *)getQRcodeImgByString:(NSString *)text withSize:(CGFloat)size{
    //创建滤镜--苹果没有将这个字符封装成常量
    CIFilter *filter=[CIFilter filterWithName:@"CIQRCodeGenerator"];
    //还原路径默认属性
    [filter setDefaults];
    //设置需要生成二维码的数据到滤镜中，OC中要求设置的是一个二进制数据
    NSData *data=[text dataUsingEncoding:NSUTF8StringEncoding];
    [filter setValue:data forKey:@"InputMessage"];
    //从滤镜中取出生成好的二维码,这里生成的二维码不够清晰，需要再处理
    CIImage *ciImage=[filter outputImage];
    return  [self createNonInterpolatedUIImageFormCIImage:ciImage withSize:size];
}

/**
 根据CIImage生成指定大小的UIImage(相比清晰一些)

 @param imgae CIImage
 @param size 图片宽度
 @return UIImage
 */
-(UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)imgae withSize:(CGFloat)size{
    CGRect extent=CGRectIntegral(imgae.extent);
    CGFloat scale=MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
    
    //创建bitmap
    size_t width=CGRectGetWidth(extent)*scale;
    size_t height=CGRectGetHeight(extent)*scale;
    CGColorSpaceRef cs=CGColorSpaceCreateDeviceGray();
    CGContextRef bitmapRef=CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);
    CIContext *context=[CIContext contextWithOptions:nil];
    CGImageRef bitmapImage=[context createCGImage:imgae fromRect:extent];
    CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
    CGContextScaleCTM(bitmapRef, scale, scale);
    //绘制图片
    CGContextDrawImage(bitmapRef, extent, bitmapImage);
    
    //保存bitmap到图片
    CGImageRef scaledImage=CGBitmapContextCreateImage(bitmapRef);
    CGContextRelease(bitmapRef);
    CGImageRelease(bitmapImage);
    //将图片颜色进行处理后返回
    return [self imageBlackToTransparent:[UIImage imageWithCGImage:scaledImage]];
    
}

void ProviderReleaseData (void *info, const void *data, size_t size)
{
    free((void*)data);
}
//图片颜色变换处理
- (UIImage*) imageBlackToTransparent:(UIImage*) image
{
    // 分配内存
    const int imageWidth = image.size.width;
    const int imageHeight = image.size.height;
    
    size_t      bytesPerRow = imageWidth * 4;
    
    uint32_t* rgbImageBuf = (uint32_t*)malloc(bytesPerRow * imageHeight);
    
    // 创建context
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(rgbImageBuf, imageWidth, imageHeight, 8, bytesPerRow, colorSpace,
                                                 kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);
    CGContextDrawImage(context, CGRectMake(0, 0, imageWidth, imageHeight), image.CGImage);
    
    // 遍历像素
    int pixelNum = imageWidth * imageHeight;
    uint32_t* pCurPtr = rgbImageBuf;
    for (int i = 0; i < pixelNum; i++, pCurPtr++)
    {
                if ((*pCurPtr & 0xFFFFFF00) == 0xffffff00)    // 将白色变成透明
//        if ((*pCurPtr & 0x65815A00) == 0x65815a00)    // 将背景变成透明
        {
            uint8_t* ptr = (uint8_t*)pCurPtr;
            ptr[0] = 0;
        }else{//其他颜色修改
            // 改成下面RGB值的代码，会将图片转成想要的颜色
            uint8_t* ptr = (uint8_t*)pCurPtr;
            //rgb 值0~255
            ptr[3] = 226;//red
            ptr[2] = 89;//green
            ptr[1] = 72;//blue
        }
    }
    
    // 将内存转成image
    CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight, ProviderReleaseData);
    CGImageRef imageRef = CGImageCreate(imageWidth, imageHeight, 8, 32, bytesPerRow, colorSpace,
                                        kCGImageAlphaLast | kCGBitmapByteOrder32Little, dataProvider,
                                        NULL, true, kCGRenderingIntentDefault);
    CGDataProviderRelease(dataProvider);
    
    UIImage* resultUIImage = [UIImage imageWithCGImage:imageRef];
    
    // 释放
    CGImageRelease(imageRef);
    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);
    
    return resultUIImage;
}

/**
 使用iOS系统自带的视频二维码图片接口，在iOS8以上可以使用

 @param qrCodeImage 二维码图片
 @return 识别出来的图片信息
 */
-(NSString *)decodeQRCodeWithImage:(UIImage *)qrCodeImage{
    CIContext *context=[CIContext contextWithOptions:nil];
    //此api有些问题，在一些机型上detector为nil
    CIDetector *detector=[CIDetector detectorOfType:CIDetectorTypeQRCode context:context options:@{CIDetectorAccuracy:CIDetectorAccuracyHigh}];
    CIImage *image=[CIImage imageWithCGImage:qrCodeImage.CGImage];
    NSArray *features=[detector featuresInImage:image];
    CIQRCodeFeature *feature=[features firstObject];
    return feature.messageString;
}