That's not the case here as I neither subclass NSObject nor overload the optional == operator. proof: swift class Month: Hashable { let name: String     internal init(name: String) {         self.name = name     }     static func == (lhs: Month, rhs: Month) - Bool {         print("Month overloaded")         return false     }     func hash(into hasher: inout Hasher) {         hasher.combine(name)     } } let a: AnyHashable = Month(name: "ab") let b: AnyHashable = Month(name: "ab") a == b // prints: `Month overloaded`

Hashable inherits - https://developer.apple.com/documentation/swift/hashable from Equatable, so no need

Which is even more weird is that it actually calls in to this block with the right data, I and the label colour is set to red, but the UI doesn't update 🤷‍♂️ could you explain please? swift dataSource = UICollectionViewDiffableDataSourceSection, Month(collectionView: collectionView) { (collectionView: UICollectionView, indexPath: IndexPath, item: Month) - UICollectionViewCell? in             let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "monthcell", for: indexPath) as! MonthCollectionViewCell             cell.label.text = item.name             cell.label.textColor = item.isSelected ? .systemRed : .systemBlue             return cell }