I was having a similar issue with a custom UIButton when the button was highlighting in grey every time it was pressed. I solved that problem by subclassing UIButton and in the implementation I overrode a single method, (void)setHighlighted: method and kept it empty:
- (void)setHighlighted:(BOOL)highlighted
{
// Leave empty to prevent super from doing whatever
// that it is doing to show the grey highlight.
}
That stopped any type of highlighting as I was not doing anything in the method. It's a better approach if all that you're trying to do is remove any highlighting effect.
So in your code, create a subclass of UIButton, override the setHighlighted method, and then make your custom button a subclass of this custom class.