iO7以上CIFilter生成二维码

#pragma mark -------QRCode begin-------//调用生成二维码接口- (UIImage *)createQRCode:(NSString *)codeContent withSize:(CGFloat)size{    //先检测图片是否存在    NSFileManager *fileManager = [NSFileManager defaultManager];    NSString * filePath = [DOCUMENT_PATH stringByAppendingPathComponent:QR_IMAGE];    filePath = [NSString stringWithFormat:@"%@.png", filePath];    if ([fileManager fileExistsAtPath:filePath])    {        return [UIImage imageNamed:filePath];    }    UIImage *qrcode = [self createNonInterpolatedUIImageFormCIImage:[self createQRForString:codeContent] withSize:size];    UIImage *customQrcode = [self imageBlackToTransparent:qrcode withRed:60.0f andGreen:74.0f andBlue:89.0f];    [self saveImage:customQrcode withFileName:QR_IMAGE ofType:@"png"];    return customQrcode;}//首先是二维码的生成，使用CIFilter很简单，直接传入生成二维码的字符串即可- (CIImage *)createQRForString:(NSString *)qrString{    NSData *stringData = [qrString dataUsingEncoding:NSUTF8StringEncoding];    // 创建filter    CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];    // 设置内容和纠错级别    [qrFilter setValue:stringData forKey:@"inputMessage"];    [qrFilter setValue:@"M" forKey:@"inputCorrectionLevel"];    // 返回CIImage    return qrFilter.outputImage;}//因为生成的二维码是一个CIImage，我们直接转换成UIImage的话大小不好控制，所以使用下面方法返回需要大小的UIImage- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size{    CGRect extent = CGRectIntegral(image.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:image fromRect:extent];    CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);    CGContextScaleCTM(bitmapRef, scale, scale);    CGContextDrawImage(bitmapRef, extent, bitmapImage);    // 保存bitmap到图片    CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);    CGContextRelease(bitmapRef);    CGImageRelease(bitmapImage);    return [UIImage imageWithCGImage:scaledImage];}//因为生成的二维码是黑白的，所以还要对二维码进行颜色填充，并转换为透明背景，使用遍历图片像素来更改图片颜色，因为使用的是CGContext，速度非常快void ProviderReleaseData (void *info, const void *data, size_t size){    free((void*)data);}- (UIImage*)imageBlackToTransparent:(UIImage*)image withRed:(CGFloat)red andGreen:(CGFloat)green andBlue:(CGFloat)blue{    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);    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) < 0x99999900)    // 将白色变成透明        {            // 改成下面的代码，会将图片转成想要的颜色            uint8_t* ptr = (uint8_t*)pCurPtr;            ptr[3] = red; //0~255            ptr[2] = green;            ptr[1] = blue;        }        else        {            uint8_t* ptr = (uint8_t*)pCurPtr;            ptr[0] = 0;        }    }    // 输出图片    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];    // 清理空间    CGImageRelease(imageRef);    CGContextRelease(context);    CGColorSpaceRelease(colorSpace);    return resultUIImage;}#pragma mark -------QRCode end-------