$ uname -a
Darwin OSX10-10.local 17.7.0 Darwin Kernel Version 17.7.0: Wed Oct 10 23:06:14 PDT 2018; root:xnu-4570.71.13~1/RELEASE_X86_64 x86_64
 
$ gcc  -v
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.14.sdk/usr/include/c++/4.2.1
Apple LLVM version 10.0.0 (clang-1000.11.45.5)
Target: x86_64-apple-darwin17.7.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

        LibRaw *rawProcessor = new LibRaw;
        CIImage *ciImage = nil;
        // Set up image processing parameters
        rawProcessor->imgdata.params.half_size = 1;
        rawProcessor->imgdata.params.user_qual = 0;
        rawProcessor->imgdata.params.use_camera_wb = 1;
        rawProcessor->imgdata.params.use_auto_wb = 0;
        rawProcessor->imgdata.params.no_auto_bright = 1;
        rawProcessor->imgdata.params.exp_correc = 1;
        rawProcessor->imgdata.params.exp_shift = 2.3;
        rawProcessor->imgdata.params.use_rawspeed = 0;
        rawProcessor->imgdata.params.user_flip = 0;     // Do not rotate image, let the caller do it
 
        if (rawProcessor->open_file([filePath UTF8String]) == LIBRAW_SUCCESS) {
            int ret = rawProcessor->unpack();
            if (ret == LIBRAW_SUCCESS) {
                ret = rawProcessor->dcraw_process();
                if (ret == LIBRAW_SUCCESS) {
                    libraw_processed_image_t *imageData = rawProcessor->dcraw_make_mem_image(&ret);
                    rawProcessor->recycle();
 
                    // make data provider from buffer
                    CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, imageData->data, imageData->data_size, NULL);
 
                    // set up for CGImage creation
                    int bitsPerComponent = imageData->bits;
                    int bitsPerPixel = imageData->bits * imageData->colors;
                    int bytesPerRow  = bitsPerPixel / 8 * imageData->width;
                    int width = imageData->width;
                    int height = imageData->height;
 
                    CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
                    CGImageRef imageRef = CGImageCreate(width, height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, kCGBitmapByteOrderDefault, provider, NULL, NO, kCGRenderingIntentDefault);
                    ciImage = [CIImage imageWithCGImage:imageRef];
                    // Free memory
                    CFRelease(colorSpaceRef);
                    CFRelease(imageRef);
                    CFRelease(provider);
                    LibRaw::dcraw_clear_mem(imageData);
                    // Auto adjust image
                    NSDictionary *options = @{ CIDetectorImageOrientation : [NSNumber numberWithInt:1],
                                               kCIImageAutoAdjustRedEye : [NSNumber numberWithBool:NO]};
                    NSArray *adjustments = [ciImage autoAdjustmentFiltersWithOptions:options];
                    for (CIFilter *filter in adjustments) {
                        // Do not apply tone curve, as it can make the contrast too high
                        if ([[filter name] isNotEqualTo:@"CIToneCurve"]) {
                            [filter setValue:ciImage forKey:kCIInputImageKey];
                            ciImage = filter.outputImage;
                        }
                    }
                }
            }
        }
        delete rawProcessor;
        return ciImage;