I have these items swift class Month: Hashable { let name: String var isSelected: Bool } I'm displaying these months in a collectionview and when tapping on one I set it's isSelected property to true and the cell should change the label's colour based on isSelected. This is how I create a new snapshot: swift func makeSnapshot() - NSDiffableDataSourceSnapshotSection, Month {         var snapshot = NSDiffableDataSourceSnapshotSection, Month()         snapshot.appendSections([Section.main])         snapshot.appendItems(months, toSection: .main)         return snapshot     } When the user taps on a cell, this happens: swift func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {     let month = dataSource.itemIdentifier(for: indexPath)     months.forEach({ $0.isSelected = false })     month?.isSelected = true dataSource.apply(makeSnapshot()) } The UI doesn't change, unless I scroll up and down (dequeue the cell again) or I call the reloadItems function. I explicitly tell the system that two months are not the same if one is selected and the other is not (and their name is the same), I expected that the UICollectionViewDiffableDataSource will use the hash and == functions to check which cells needs to be reloaded, however this clearly is not the case. Although, when I replace the instance itself, it will reload the cell (same happens if I mutate structs instead of classes). The hash/== functions: swift extension Month { func hash(into hasher: inout Hasher) {     hasher.combine(name)     hasher.combine(isSelected) } static func == (lhs: DemoViewController.Month, rhs: DemoViewController.Month) - Bool {     lhs.name == rhs.name && lhs.isSelected == rhs.isSelected         } } This makes me think that the system compares the memory addresses and not the hash/equality of the items. Can you please confirm if this is the case. Since I provide all the information needed to work out the difference between a new and an old snapshot I expected that the UICollectionViewDiffableDataSource is smarter and encapsulates this logic and I don't have to write the additions/deletions/reorders/replacements logic every single time I use this API. Thanks a lot, Bence