hi, is there a recommended way to consume a `State...

# mvikotlin

[Travis Reitter]

hi, is there a recommended way to consume a State directly from SwiftUI (ie, avoiding the State -> Model translation and avoiding creating a class that implements BaseMviView)? My project's equivalent of MainController in the sample exposes a Flow<State> that I consume directly from Compose with Flow<T>.collectAsStateWithLifecycle() and I'd like to follow as closely as possible with my SwiftUI

[Travis Reitter]

I found one option for translating a Flow to a Publisher that seems OK but requires new boilerplate code for every Flow instance but the article is 2 years old so I don't know if there's a simpler option available now (or, especially, a solution geared toward MVIKotlin usage)

[Arkadii Ivanov]

In this case you could expose it as something like CFlow wrapper, and observe it as usual in SwiftUI.

[Arkadii Ivanov]

So I would define CStateFlow wrapper in the shared module and wrap the Store's StateFlow. Then convert it to ObservableObject in Swift.

[Travis Reitter]

ah, so like the pattern used in this example?:
• app
• store
• CFlow
• util

[Arkadii Ivanov]

Yes something like this! Except maybe the naming. I would create a Kotlin class like:

class WrappedStateFlow<T : Any>(
    source: Flow<T>,
    private val context: CoroutineContext = Dispatchers.Main.immediate,
) : StateFlow<T> by source {
    fun subscribe(onNext: (T) -> Unit): Cancellation {
        val scope = CoroutineScope(context)
        scope.launch { collect(onNext) }
        return Cancellation { scope.cancel() } 
    }

    fun interface Cancellation {
        fun cancel()
    }
}

[Arkadii Ivanov]

You can also define an extension like fun <T : Any> StateFlow<T>.wrap(): WrappedStateFlow<T> = WrappedStateFlow(this)
And just expose WrappedStateFlow instead of StateFlow.

[Travis Reitter]

great, thank you!

[Travis Reitter]

just to be sure, the source param should be defined as source: StateFlow<T>, right?

[Arkadii Ivanov]

Oh correct!

[Arkadii Ivanov]

I wrote that code in Slack 😀

[Travis Reitter]

😄

[Travis Reitter]

I'm still trying to parse fun interface Cancellation. I guess it's a work-around for the fact that interfaces can't be instantiated? I'm just surprised that works :)

[Arkadii Ivanov]

That just to shorten the instantiation 😀 just a shorter syntax for anonymous object.

[Travis Reitter]

ah, yeah. I would have used object : since I didn't know about this shortcut

[Arkadii Ivanov]

Just make sure you are collecting the flow on Main.immediate dispatcher, as updating the state synchronously on the same call stack is very important sometimes (avoids glitches with text fields, etc.)