This article has been archived, as it was published several years ago, so some of its information might now be outdated. For more recent articles, please visit the main article feed.
Specializing protocols using constraints
Basics article available: ProtocolsA little late night prototyping session reveals that protocol constraints can not only be applied to extensions - they can also be added to protocol definitions!
This is awesome, since it lets us easily define specialized protocols based on more generic ones.
protocol Component {
associatedtype Container
func add(to container: Container)
}
// Protocols that inherit from other protocols can include
// constraints to further specialize them.
protocol ViewComponent: Component where Container == UIView {
associatedtype View: UIView
var view: View { get }
}
extension ViewComponent {
func add(to container: UIView) {
container.addSubview(view)
}
}
Swift by Sundell is brought to you by the Genius Scan SDK — Add a powerful document scanner to any mobile app, and turn scans into high-quality PDFs with one line of code. Try it today.