Model-View-View Model in Swift

Srdan Rasic wrote a good post on creating wrappers around value objects (like Strings, say) and custom-glue them to an application’s interface. It’s a technique I have used in my book on Mac architecture at one point but which seems to be tremendously useful for virtually anything view-related once you get to a high enough level of abstraction.

It’s weird that articles related to programming are so hard to quote. Instead of a quotation, let the resulting code illustrates what he has to say:

class ArticleViewController {
  var bodyTextView: UITextView
  var titleLabel: UILabel
  var dateLabel: UILabel
  var thumbnailImageView: UIImageView
   
  var viewModel: ArticleViewViewModel {
    didSet {
      viewModel.title.bindAndFire {
        [unowned self] in
        self.titleLabel.text = $0
      }
   
      viewModel.body.bindAndFire {
        [unowned self] in
        self.bodyTextView.text = $0
      }
   
      viewModel.date.bindAndFire {
        [unowned self] in
        self.dateLabel.text = $0
      }
   
      viewModel.thumbnail.bindAndFire {
        [unowned self] in
        self.thumbnailImageView.image = $0
      }
    }
  }
}

So now when viewModel’s properties change, the view controller will update the corresponding interface component. Sweet.

Exploring Mac App Development Strategies – Patterns & Best Practices for Clean Software Architecture on the Mac. Don’t worry about big software design decisions anymore. Take on Mac app development with solid principles, guided by extensive examples and explanation. Buy the book now!