Using a different renderer besides UIKit

[michaeleisel]

Given the instantiation cost of UIViews and delays in rendering, both of which must be done on the main thread, it'd be cool to support an alternate renderer. It could be one that's thread-safe, does less work, or both. Perhaps Flutter's Skia would be worth playing with, which I've heard anecdotally can be faster.

[erichoracek]

Hi Michael, first off thanks for submitting an issue to Epoxy!

In terms of supporting an alternate renderer, I would say that Epoxy is most definitely tightly coupled to UIKit for rendering, so something like an alternate renderer would be out of scope for this project as it would dramatically increase the scope of Epoxy beyond being a set of declarative adapters written atop UIKit APIs like UICollectionView, UIStackView, etc.

We've found UIKit to meet our needs in terms of performance despite rendering occurring on the main thread. Auto Layout has had a number of great performance improvements over the years, and UIKit's ability to hand off most animations to the render server gives us a smooth 60 FPS in most cases.

[erichoracek]

You might find https://github.com/TokamakUI/Tokamak interesting, which is a Swift declarative UI framework that supports custom platform-specific renderers.

[michaeleisel]

To elaborate, I agree that scrolling performance is a fairly solved problem. My concern is more around creating the views for a new screen, especially during startup. This is a case where I think everyone is dropping frames. But I understand not wanting to try a whole new renderer for this as well.