iOS - How to set corner radius in UIImage fill color ?

- (UIImage *) clearPixel1 {
  CGRect rect = CGRectMake(0.0, 0.0, 25.0, 27.0);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [[UIColor lightGrayColor] CGColor]);
    CGContextFillRect(context, rect);
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}