Question

For some reason, the button initialized in the addBook method of my viewController won’t respond to touches. The selector I’ve assigned to it never triggers, nor does the UIControlStateHighlighted image ever appear when tapping on the image.

Is there something intercepting touches before they get to the UIButton, or is its interactivity somehow disabled by what I’m doing to it?

- (void)viewDidLoad {

    ...

    _scrollView.contentSize = CGSizeMake(currentPageSize.width, currentPageSize.height);
    _scrollView.showsHorizontalScrollIndicator = NO;
    _scrollView.showsVerticalScrollIndicator = NO;
    _scrollView.scrollsToTop = NO;
    _scrollView.pagingEnabled = YES;

    ...
}

- (void)addBook {
    // Make a view to anchor the UIButton
    CGRect frame = CGRectMake(0, 0, currentPageSize.width, currentPageSize.height);
    UIImageView* bookView = [[UIImageView alloc] initWithFrame:frame];

    // Make the button
    frame = CGRectMake(100, 50, 184, 157);
    UIButton* button = [[UIButton alloc] initWithFrame:frame];
    UIImage* bookImage = [UIImage imageNamed:kBookImage0];

    // THIS SECTION NOT WORKING!
    [button setBackgroundImage:bookImage forState:UIControlStateNormal];
    UIImage* bookHighlight = [UIImage imageNamed:kBookImage1];
    [button setBackgroundImage:bookHighlight forState:UIControlStateHighlighted];
    [button addTarget:self action:@selector(removeBook) forControlEvents:UIControlEventTouchUpInside];

    [bookView addSubview:button];   
    [button release];
    [bookView autorelease];

    // Add the new view/button combo to the scrollview.
    // THIS WORKS VISUALLY, BUT THE BUTTON IS UNRESPONSIVE :(
    [_scrollView addSubview:bookView];
}

- (void)removeBook {
    NSLog(@"in removeBook");
}

The view hierarchy looks like this in Interface Builder:

UIWindow
UINavigationController
    RootViewController
        UIView
            UIScrollView
            UIPageControl

and presumably like this once the addBook method runs:

UIWindow
UINavigationController
    RootViewController
        UIView
            UIScrollView
                UIView
                    UIButton
            UIPageControl

Answer 1

THe UIScrollView might be catching all the touch events.

Maybe try a combination of the following:

_scrollView.delaysContentTouches = NO;
_scrollView.canCancelContentTouches = NO;

and

bookView.userInteractionEnabled = YES;