How to add a binding gesture to a UICollectionView, while maintaining cell selection?

Question

Task

Add one sign gestures to the UICollectionView ; don't interfere with cell selection.

I want some other taps on the non-element part of the View collection.

The code

Using Xcode8, Swift 3.

 override func viewDidLoad() { ... collectionView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(tap))) } func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) { print(indexPath) } func tap(sender: UITapGestureRecognizer){ print("tapped") } 

Result

Yes, now it interferes. When you click on a cell, it records "tapping."

Analysis

• I check the return value of the hitTest of the collection and cell. Both returned the selected cell, which means that they form a chain of responders Cell → CollectionView
• no gestures in the cell
• 3 gestures in the View collection, no one works with cell selection
  • UIScrollViewDelayedTouchesBeganGestureRecognizer
  • UIScrollViewPanGestureRecognizer
  • UITapGestureRecognizer
• callStack, it seems that the cell selection has a different stack trace with the target gesture action pattern.
• A double-tap gesture works with cell selection.

Question

Could not find more trace. Any ideas on how cell selection is done or to achieve this?

Answer 1

Whenever you want to add a gesture recognizer, but do not steal strokes from the target view, you must set UIGestureRecognizer.cancelsTouchesInView for your gestureRecognizer instance to false.

Answer 2

Instead of trying to force didSelectItem you can simply get indexPath and / or cell as follows:

 func tap(sender: UITapGestureRecognizer){ if let indexPath = self.collectionView?.indexPathForItem(at: sender.location(in: self.collectionView)) { let cell = self.collectionView?.cellForItem(at: indexPath) print("you can do something with the cell or index path here") } else { print("collection view was tapped") } }