ios horizontal scroll menu - background buttons select - ios

Question

I try to make an horizontal navigation menu in scrollView. For every items in the menu i had a different image. When i select an item, i would like to change background image of this item, but i don't know why my code doesn't work:
for (int i=0; i<12; i++) {
UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
UIImage *normal=[UIImage imageNamed:#"icon1"];
UIImage *selec=[UIImage imageNamed:#"icon1down"];
[btn setFrame:CGRectMake(i*larg, 0, 42.0, 43.0)];
[btn setBackgroundImage:normal forState:UIControlStateNormal];
[btn setBackgroundImage:selec forState:UIControlStateSelected];
[scrollCat addSubview:btn];
cx+=42.0;
}
[scrollCat setContentSize:CGSizeMake(cx, 43)];
Is there a bad thing in this code?

Answer 1

Try UIControlStateHighlighted instead of UIControlStateSelected.
Highlighted is the state when the user touches your button.
Selected is only used for some controls, like segments ; a custom button (one that say, stays selected) would/could make use of Selected.
From the UIControl_Class docs at developer.apple.com (emphasis mine):
UIControlStateHighlighted
Highlighted state of a control. A control enters this state when a
touch enters and exits during tracking and when there is a touch up
event. ...
UIControlStateSelected
Selected state of a control. For many controls, this state has no
effect on behavior or appearance. But other subclasses (for example,
the UISegmentedControl class) may have different appearance depending
on their selected state. ...