What does this do that can't be done in the built in previewer? Just curious, as I thought storybook solves a problem that didn't exist in iOS

[technoplato]

No description provided.

[JohnEstropia]

For one, the preview only lets us check visually. If you want to test "look and feel", as well as complex animations, you will have to test in a device. Also, anybody in the team (designers, Android engineers, etc) not just iOS devs can playtest and evaluate the components directly without the need for Xcode and other dev environments.

In our case, we also follow a design system and the tactile prototypes make engineer-designer feedback a lot smoother.

[muukii]

Following @JohnEstropia 's reply.

built in previewer

Meaning, it seems Xcode Preview function, right?
Actually, it's optimized for SwiftUI's view, so this library is focusing on previewing and interacting with UIKit-based components.

Of course, with some tricks, we could preview such components in Xcode Preview. Although it does not work well in some complex project.
Still, running the actual application to preview further works well.