Kotlin Multiplatform support

[blakelee]

I was messing around with workflow to see if I could get it working for a KMP project and I managed to get it working for Compose Multiplatform. I was trying to manage state for a personal app I'm making and after seeing the existing solutions recommended on jetbrains' website, I decided it was worth a shot to see if I could make it myself. Here is a simple hello world showing it working

How did I do it?

1. I noticed that workflow-core and workflow-runtime already supported KMP.
2. I noticed that @MilanJovic92 made a post here to move some more code to a module that supports KMP, so I made my own module with just the classes mentioned.
3. The only thing left was the workflow-ui/compose module so I imported all of those classes except for ViewEnvironmentWithComposeSupport.kt and removed the functions related to ViewFactory in ScreenComposableFactory.kt which left me with POKO's and nothing Android related.
4. At this point there was a small issue, I needed access to LocalLifecycleOwner in WorkflowRendering.kt but I needed a KMP solution. There was also this recent change which caused some friction. LocalLifecycleOwner was moved to androidx.lifecycle:lifecycle-runtime-compose which doesn't have KMP binaries. Luckily for us Jetbrains just released their own version for KMP here which is available in the Compose plugin 1.6.10.
5. Now that I have access to the current lifecycle compose.ui in the compose plugin as well as org.jetbrains.androidx.lifecycle:lifecycle-runtime-compose, I could edit WorkflowRendering.kt to support our KMP lifecycle. Simply import androidx.lifecycle.compose.LocalLifecycleOwner then modify the function rememberChildLifecycleOwner where the parentLifecycle will now be androidx.compose.ui.platform.LocalLifecycleOwner.current.lifecycle
6. You now have access to workflow in Compose multiplatform.

I faced a lot of dependency issues trying to figure this out. So as of right now I could only get it working on Android and iOS with Kotlin 2.0.0, Compose-plugin 1.6.10 and Lifecycle-runtime-compose 2.8.0.

If we wanted to make these changes public, we'd have to take the Android code out of workflow-ui/compose and possibly make another module for the Android View factories.

[blakelee]

Here's a sample project with it running https://github.com/blakelee/WorkflowMultiplatform