Secret SwiftUI: A practical use for _VariadicView

I finally found a use case for this private API

I’m kind of late to the party on this, frankly.

_VariadicView helps us create custom VStacks. Our own flexible tab bars. Bespoke pickers and lists. I started writing this article in March 2024, but was stumped trying to find a non-contrived example—one that would actually be useful in production.

While mulling it over on a mental background thread, this article faded into a dusty backlog alongside aborted magnum opi such as Through The Ages: Apple Concurrency APIs and Dumb Ways To Maximise Your App Binary Size.

Recently, that all changed.

At midnight, I was doing what we all do once our wives fall asleep: reading Vincent Pradeilles. Specifically, his article on building inverted scroll for messaging apps.

Inspiration struck. I finally realised a practical use case for _VariadicView: a reusable ChatList component that automatically applies scroll inversion on the contents.

Today, much like our scrolling, let’s work backwards.

We’ll implement a scroll inversion, and experience the pain point together as our UI grows more complicated. Only then will I introduce _VariadicView, take you under the covers to explain how it all works, then demonstrate how you can use _VariadicView to address this specific pain point in your own apps.