Functions to convert an NSImage (*pattern image*) to a CGColorRef color, following the advice from http://stackoverflow.com/questions/2520978/how-to-tile-the-contents-of-a-calayer

NSimageToCGColorRef.mm

/* http://stackoverflow.com/questions/2520978/how-to-tile-the-contents-of-a-calayer  */

// callback for CreateImagePattern.
static void DrawPatternImage (void *info, CGContextRef ctx) {
    CGImageRef image = (CGImageRef) info;
    CGContextDrawImage(ctx,
                       CGRectMake(0,0, CGImageGetWidth(image),CGImageGetHeight(image)),
                       image);
}

// callback for CreateImagePattern.
static void ReleasePatternImage( void *info ) {
    CGImageRelease((CGImageRef)info);
}

CGColorRef CreateCGColorWithPatternFromNSImage( NSImage *image ) {
    /* User needs to release the color  */
    
    NSData *imageData = [image TIFFRepresentation];
    CFDataRef cfImageData = CFBridgingRetain(imageData);
    CGImageSourceRef source = CGImageSourceCreateWithData(cfImageData, NULL);
    CGImageRef cgImage =  CGImageSourceCreateImageAtIndex(source, 0, NULL);
    CFRelease(cfImageData);
    CFRelease(source);
    
    
    //assume image is the CGImage you want to assign as the layer background
    CGFloat width = [image size].width;
    CGFloat height = [image size].height;
    static const CGPatternCallbacks callbacks = {0, &DrawPatternImage, &ReleasePatternImage};
    CGPatternRef pattern = CGPatternCreate (cgImage,
                                            CGRectMake (0, 0, width, height),
                                            CGAffineTransformMake (1, 0, 0, 1, 0, 0),
                                            width,
                                            height,
                                            kCGPatternTilingConstantSpacing,
                                            true,
                                            &callbacks);
    CGColorSpaceRef space = CGColorSpaceCreatePattern(NULL);
    CGFloat components[1] = {1.0};
    CGColorRef color = CGColorCreateWithPattern(space, pattern, components);
    CGColorSpaceRelease(space);
    CGPatternRelease(pattern);
    return color;
}