Does anyone have a good writeup or documentation for how Compose Multiplatform for iOS works? As in...

# compose-ios

[Richard L Zarth III]

Does anyone have a good writeup or documentation for how Compose Multiplatform for iOS works? As in: how does code/rendering get transformed from Compose to UIKit and/or SwiftUI code/rendering (not from a How Do I standpoint but from a curiosity standpoint)? Any resources would be appreciated, thanks. 🙂

[Stefan Oltmann]

Nothing gets transformed. The approach is rather simple and the same like Flutter or Compose Desktop: Rendering using SKIA to a canvas. Same is true for Compose for Web.

[Stefan Oltmann]

Transforming to SwiftUI would be a possibility, but that way you would have to deal with all the limitations of SwiftUI. For example in SwiftUI you can't set a scrollstate to a scrollview. If you have a working Android/JVM app using that feature the Apple version would lack this functionality if Compose UI would be converted/adapted to SwiftUI.

[Richard L Zarth III]

So to make sure that I understand: Compose Multiplatform takes its components, renders them via Skia on a Canvas, and then for iOS creates a UIViewController whose UIView is just a "drawing board" for that Canvas. So from the UIKit perspective there is just one UIViewController and UIView at all times essentially. Does that seem accurate?

[Stefan Oltmann]

That's how I understood that process, yes.

[Stefan Oltmann]

The UIView is the canvas in that case.
On JVM it's a JComponent (Swing) that serves as the canvas.

[Stefan Oltmann]

But I would also be interested in resources that explain how exactly SKIA is utilized to draw to UIView and JComponent.

[Alejandro Rios]

Here's a related topic, it might help

[Richard L Zarth III]

Thanks. 👍

[Richard L Zarth III]

Is this the same Canvas: https://developer.android.com/reference/kotlin/androidx/compose/ui/graphics/Canvas

[Stefan Oltmann]

That Canvas component is used here to create a MapView.
So it's just a way to build custom views.

https://github.com/JetBrains/compose-multiplatform/blob/73171a0f9e0f62b4db9c7dfcbc[…]r/mapview-desktop/src/desktopMain/kotlin/example/map/MapView.kt

[Richard L Zarth III]

Thanks. 👍

[Dima Avdeev]

Some info about Compose for iOS architecture available on KotlinConf talk:

https://youtu.be/03T-ARIo0t8?t=18811▾

Later we will provide some additional docs about the usage of Compose for iOS. (But not about arhitecture)

[Richard L Zarth III]

Thanks for the video. I'll check it out.