super respondsToSelector: returns true but actually calling super (selector) gives “unrecognized selector sent to instance”

Question

OK, I am a little confused.

I have a subclass of UIScrollView, which is my attempt at a horizontally scrolling \"table view\" like UI element. UIScrollView itself s

Answer 1

As a summary for someone with the same case, there are two problems in the original question:

1. Checking whether the superclass responds to that selector, which as suggested by @jjburka is best done by using instancesRespondToSelector:.
2. Actually invoking the method on the superclass without the compiler complaining even though it's declared in a private header. This can be neatly achieved by redeclaring it in a category (see this question).

Putting it together this gives:

// … In subclass implementation file
@interface UIScrollView ()  @end

// … In gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer:
if ([UIScrollView instancesRespondToSelector:@selector(gestureRecognizer:shouldRecognizeSimultaneouslyWithGestureRecognizer:)]) {
    return [super gestureRecognizer:gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:otherGestureRecognizer];
}