Saturday, December 12, 2015 [Tweets] [Favorites]

Humble Object Pattern in Swift

Alexei Kuznetsov (comments):

The outside world can just tell [the view controller] to show some data and doesn’t have to know about the UIKit-specific details of presenting it. All labels, text fields, and image views are encapsulated inside a view controller, and only strings and images are exposed.

What’s left in the view controller is a simple mapping of values it receives from the outside to the UI elements of the view it controls. The view controller becomes very humble.

See also: The Clean Architecture:

The overriding rule that makes this architecture work is The Dependency Rule. This rule says that source code dependencies can only point inwards. Nothing in an inner circle can know anything at all about something in an outer circle. In particular, the name of something declared in an outer circle must not be mentioned by the code in the an inner circle. That includes, functions, classes. variables, or any other named software entity.

By the same token, data formats used in an outer circle should not be used by an inner circle, especially if those formats are generate by a framework in an outer circle. We don’t want anything in an outer circle to impact the inner circles.

Previously: Making a Mockery with Mock Objects.

2 Comments

Stay up-to-date by subscribing to the Comments RSS Feed for this post.

Leave a Comment