Output Port Adapter for Single Point of Configuration in Complex UI

When you have nested and complex UI components with multiple sub-view controllers, passing an optional output port (event handler or delegate) down the tree is cumbersome. There are two straight-forward approaches: The second option is “cleaner”, but for a two or three object component might also feel a bit too much.
Iteratively Improving Your App: Decoupling Components at Module Seams and Adding Facades

Façades are very important tools when I flesh-out the modules of an application. They turn out to be only the logical consequence of basic object-oriented programming principles, internal cohesion of objects namely, paired with decoupling of application modules (like “model” and “view”). Take a complex view that has many subviews. When you need to update a single piece of the user interface, how do you get there?