Function for Complementary color form RGBA color

[slcott]

I'd like a function like the following for the Colours category you've created:

- (UIColor *)complementarySecondaryColorForColor:(UIColor *)primaryColor
{
    UIColor *secondaryColor;

    // calculated secondary complement

    return secondaryColor;
}

I would love if this code was written for objective-C.

Perhaps I'll just create it myself.