To Generate a UIImage of a UIColor. Useful when you want to change the background color of a UIButton

imageWithColor

- (UIImage *)imageWithColor:(UIColor *)color {
    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;
}

// http://stackoverflow.com/questions/14523348/how-to-change-the-background-color-of-a-uibutton-while-its-highlighted