```swift import IGListKit final class Comment: ListDiffable { let username: String let text: String init(username: String, text: String) { self.username = username self.text = text } // MARK: ListDiffable func diffIdentifier() -> NSObjectProtocol { return (username + text) as NSObjectProtocol } func isEqual(toDiffableObject object: ListDiffable?) -> Bool { return true } } ``` A note on the `isEqual(toDiffableObject:)` implementation: Whatever you use to derive the `diffIdentifier` can be omitted from any equality checks, since by definition the objects have already matched on their identifiers. In this case, the `username` and `text` **must be equal** by the time two objects are checked for equality.
```swift import IGListKit final class ImageViewModel: ListDiffable { let url: URL init(url: URL) { self.url = url } // MARK: ListDiffable func diffIdentifier() -> NSObjectProtocol { return "image" as NSObjectProtocol } func isEqual(toDiffableObject object: ListDiffable?) -> Bool { guard let object = object as? ImageViewModel else { return false } return url == object.url } } final class ActionViewModel: ListDiffable { let likes: Int init(likes: Int) { self.likes = likes } // MARK: ListDiffable func diffIdentifier() -> NSObjectProtocol { return "action" as NSObjectProtocol } func isEqual(toDiffableObject object: ListDiffable?) -> Bool { guard let object = object as? ActionViewModel else { return false } return likes == object.likes } } ``` > You could try getting away with using generics since these models look so similar, but we've found that using **simple** models makes long-term maintenance more manageable.
```swift
func sectionController(
_ sectionController: ListBindingSectionController
```swift final class ActionCell: UICollectionViewCell, ListBindable { @IBOutlet weak var likesLabel: UILabel! @IBOutlet weak var likeButton: UIButton! // MARK: ListBindable func bindViewModel(_ viewModel: Any) { guard let viewModel = viewModel as? ActionViewModel else { return } likesLabel.text = "\(viewModel.likes)" } } final class UserCell: UICollectionViewCell, ListBindable { @IBOutlet weak var usernameLabel: UILabel! @IBOutlet weak var dateLabel: UILabel! // MARK: ListBindable func bindViewModel(_ viewModel: Any) { guard let viewModel = viewModel as? UserViewModel else { return } usernameLabel.text = viewModel.username dateLabel.text = viewModel.timestamp } } final class CommentCell: UICollectionViewCell, ListBindable { @IBOutlet weak var usernameLabel: UILabel! @IBOutlet weak var commentLabel: UILabel! // MARK: ListBindable func bindViewModel(_ viewModel: Any) { guard let viewModel = viewModel as? Comment else { return } usernameLabel.text = viewModel.username commentLabel.text = viewModel.text } } ```
