iOS 图片去除特定背景色，使背景透明

//去除图片的粉色背景

- (UIImage*) imageToTransparent:(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++)
        
    {
     
        //接近粉色
        
        //将像素点转成子节数组来表示---第一个表示透明度即ARGB这种表示方式。ptr[0]:透明度,ptr[1]:R,ptr[2]:G,ptr[3]:B
        
        //分别取出RGB值后。进行判断需不需要设成透明。
        
        uint8_t* ptr = (uint8_t*)pCurPtr;
        // NSLog(@"1是%d,2是%d,3是%d",ptr[1],ptr[2],ptr[3]);
        if(ptr[1] >= 200 || ptr[2] >= 200 || ptr[3] >= 200){
             ptr[0] = 0;
        }

        
    }
    
    // 将内存转成image
    
    CGDataProviderRef dataProvider =CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight, nil);
    
    
    
    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;
    
}