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

After looking at the other answers, the best solution is to use [[MapControllerSublcass1 superclass] instancesRespondToSelector:_cmd]. If you use what is recommended above, something like [BaseClass instancesRespondToSelector:_cmd], you run into the problem of changing your class hierarchy and accidentally forgetting to change BaseClass to the new superclass or your subclass.

[[self superclass] instancesRespondToSelector:...] is incorrect as explained above in the comments and it actually says so on Apple's documentation (See respondsToSelector: in NSObjct). It only works when you have 1 level of subclassing, so it gives you the illusion that it is an actual solution. I fell for it.

And [[super class] instancesRespondToSelector:...] doesn't work and is the whole point of this SO question.

For example, I have a BaseMapController that implements some of the methods in MKMapViewDelegate, but it doesn't implement mapView:regionWillChangeAnimated:. MapControllerSublcass1 inherits from BaseMapController. And MapControllerSubclass2 inherits from MapControllerSublcass1.

In my code I have something like this, and it works fine.

MapControllerSublcass1.m:

- (void)mapView:(MKMapView *)mapView regionWillChangeAnimated:(BOOL)animated {
  if ([[MapControllerSublcass1 superclass] instancesRespondToSelector:_cmd]) {
    [super mapView:mapView regionWillChangeAnimated:animated];
  }
}

MapControllerSubclass2.m:

- (void)mapView:(MKMapView *)mapView regionWillChangeAnimated:(BOOL)animated {
  if ([[MapControllerSubclass2 superclass] instancesRespondToSelector:_cmd]) {
    [super mapView:mapView regionWillChangeAnimated:animated];
  }
}