Has this problem been resolved yet? Still can't figure it out!

I'm also using MAConfirmButton. I think that's happening because UIColor has a method now, which wasn't present when the UIColor-Expanded category was created.
You can check where this method is used in MAConfirmButton code. If it's not used anywhere (my bet) you can freely remove it. If it is used somewhere, remove it with caution after a check that the method in UIColor does the same job.

But when I comment out the method, in the UIColor-Extended class, the buttons tint color turns red from yellow. Here is the method that's causing all the trouble:

+ (UIColor *)colorWithHue:(CGFloat)hue saturation:(CGFloat)saturation brightness:(CGFloat)brightness alpha:(CGFloat)alpha {
    // Convert hsb to rgb
    CGFloat r,g,b;
    [self hue:hue saturation:saturation brightness:brightness toRed:&r green:&g blue:&b];

    // Create a color with rgb
    return [self colorWithRed:r green:g blue:b alpha:alpha];
}

When I'm creating the MAConfirmButton I use the colorWithRed:(CGFloat)red green:(CGFloat)green blue:(CGFloat)blue alpha:(CGFloat)alpha;

In the method causing the trouble you convert it to be the above method. Any thoughts on this?

If you are on a tight schedule I suggest you just to rename that conflicting method, and also rename all occurrences of it in MAConfirmButton code.

I don't use -setTint: in MAConfirmButton that's why I haven't that issue you are experiencing.

Looking deeper you may notice that this UIColor-Extended category provides it own getters for hue, saturation and brightness which MAConfirmButton also uses. So I think the problem is that MAConfirmButton must use HSB getters from UIColor also if this is possible, or UIColor-Extended method names must be changed to not conflict with iOS API.

This is in fact a huge bug on iOS 6. Confirmed.

PR forthcoming.

This is actually worse than I thought. This method has existed since iOS 2.0.

http://developer.apple.com/library/ios/#documentation/uikit/reference/UIColor_Class/Reference/Reference.html

Yuck.