Quick example project to reproduce this issue: https://stackoverflow.com/questions/74194162/uicollectionview-subclass-with-internal-delegate-doesnt-get-triggered-when-exte
When the delegate method is not implemented on the CustomCollectionView, the ViewController is unable to call this method. this results in the problem that the CustomCollectionView needs to implement all delegate methods which is not very future proof.
thoughts? @DonMag