Uninstall existing gesture recognizers when calling setupCollectionView #117

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1. ryderjack commented on Jul 23, 2018

   

   ryderjack

   on Jul 23, 2018

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   I'm seeing this too, what's your solution @acruis ?
2. acruis commented on Jul 23, 2018

   

   acruis

   on Jul 23, 2018

   Last edited by acruis

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   For now I'm working around it by only injecting the layout in the init (basically the snippet below "instead of this").

   If you have to set the collectionViewLayout manually then...I'm not sure there's much you can do. The layout does expose its gesture recognizers but setupCollectionView sets the ivars directly instead of calling the property setters, which means you can't rely on KVO.

   Off the top of my head I have some wild hacks, but none of them are that nice:

   • Since the KVO method has a check for if (self.collectionView != nil) {, you can subclass LXReorderableCollectionViewFlowLayout and override the getter of collectionView, which lets you run some code before the gesture recognizers go stale, something like:

   class CustomFlowLayout: LXReorderableCollectionViewFlowLayout {
       var settingCollectionView: Bool = false
       override var collectionView: UICollectionView? {
           let collectionView = super.collectionView
           if let gestureRecognizer = self.panGestureRecognizer, self.settingCollectionView {
               collectionView?.removeGestureRecognizer(gestureRecognizer)
           }
           return collectionView
       }
   }
   
   ...
   
   // (when setting the flow layout)
   let reorderableFlowLayout = CustomFlowLayout()
   reodrerableFlowLayout.settingCollectionView = true
   collectionView.collectionViewLayout = reorderableFlowLayout
   reorderableFlowLayout.settingCollectionView = false

   I haven't tried this myself, so I'm not sure if it even works though.

   • You might also be able to subclass UICollectionView to override the addGestureRecognizer call to somehow keep track of existing gesture recognizers and remove stale ones accordingly, but if you go that far...
   • ...you might as well just make copies of the collection view and switch between them when you need to change the layout.