UICollectionview is loaded with simple cells and there is a simple int variable for calculating the number of items in the section.
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int { return viewCount } When the value of viewCount (initially at 45) is changed to a lower number (say 12) the app crashes.
This is error message to update the item count:
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UICollectionView received layout attributes for a cell with an index path that does not exist: <NSIndexPath: 0x17402fbe0> {length = 2, path = 0 - 12}' I tried reloading data and invalidating the cache as well as said here. This didn't help. I also tried reloading the indexSet before invalidating the cache. That didn't help either.
func textFieldShouldReturn(_ textField: UITextField) -> Bool { if textField == countTextField { viewCount = Int(textField.text!)! textField.resignFirstResponder() let indexSet = IndexSet(integer: 0) // collectionView.reloadSections(indexSet) collectionView.reloadData() collectionView.collectionViewLayout.invalidateLayout() } return true } I use 2 custom UICollectinViewLayout and I also set shouldInvalidateLayout to be true. Any help?
Update
func numberOfSections(in collectionView: UICollectionView) -> Int { return 1 } func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell { let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "DemoCell", for: indexPath) as! DemoCollectionViewCell cell.indexLabel.text = "\(indexPath.item + 1)" return cell } @IBAction func showLayout1(_ sender: Any) { currentLayout = DemoACollectionViewLayout() animateLayout() } @IBAction func showLayout2(_ sender: Any) { currentLayout = DemoBCollectionViewLayout() animateLayout() } func animateLayout() { UIView.animate(withDuration: 0.3) { [weak self] value in guard let `self` = self else { return } self.collectionView.collectionViewLayout.invalidateLayout() self.collectionView.collectionViewLayout = self.currentLayout! } } Here is the sample project.
Update: I have updated to use an dataObject to reload the UICollectionView but the cache in UICollectionViewLayout is not being cleared when I invalidate.
1 Answers
Answers 1
The cache must be cleared when the number of items for the collectionView has changed.
guard let views = collectionView?.numberOfItems(inSection: 0) else { cache.removeAll() return } if views != cache.count { cache.removeAll() } if cache.isEmpty { //Layout attributes } 
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