You want to add your own gesture recognizers, such as pinch gesture recognizers, to a collection view in order to enable custom behaviors on top of the existing ones.
Instantiate your gesture recognizer and then go through all the
existing collection view gesture recognizers to see whether a gesture
recognizer similar to yours already exists. If so, call the
requireGestureRecognizerToFail: method on the
existing gesture recognizer and pass your own recognizer as the
parameter to this method. This will ensure that the collection view’s
gesture recognizer that is similar to yours will grab the gestures only
if your gesture recognizer fails to process its data or its
requirements/criteria aren’t met. That means that if your gesture
recognizer can process the gesture, it will, but if it cannot, the
gesture will be sent to the collection view’s existing gesture
recognizers for processing.
Once this is done, add your gesture recognizer to your collection
view. Remember, in an instance of
UICollectionViewController, your collection
view object is accessible through the
collectionView property of the controller and
The iOS API has already added a few gesture recognizers to collection views. So in order to add your own gesture recognizers, on top of the existing collection, you first need to make sure that your gesture recognizers will not interfere with the existing ones. To do that, you have ...