Daniyar Gabbasov

- (UIImage*)convertToInverseWhiteMask: (UIImage *) image {
    UIGraphicsBeginImageContextWithOptions(image.size, NO, image.scale);
    CGRect imageRect = CGRectMake(0.0f, 0.0f, image.size.width, image.size.height);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    
    // Draw a white background (for white mask)
    CGContextSetRGBFillColor(ctx, 0.0f, 0.0f, 0.0f, 0.75f);
    CGContextFillRect(ctx, imageRect);
    
    
    // Apply the source image's alpha
    [image drawInRect:imageRect blendMode:kCGBlendModeDestinationOut alpha:1.0f];
    CGContextScaleCTM(ctx, 1.0, -1.0);
    UIImage* mask = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return mask;
}