UIButton color change
myButton.backgroundColor = [UIColor brownColor];

myButton.backgroundColor = [UIColor colorWithHue:1.0/12 saturation:2.0/3 brightness:4.0/10 alpha:1];

UIColor *color = UIColor.brownColor;
CGFloat hue, saturation, brightness, alpha;
[color getHue:&hue saturation:&saturation brightness:&brightness alpha:&alpha];
brightness *= .8;
UIColor *darkerColor = [UIColor colorWithHue:hue saturation:saturation brightness:brightness alpha:alpha];

UIColor *myColor = [UIColor colorWithRed:0.5f green:0.5f blue:0.5f alpha:1.0f];