hey all, I'm running into an interesting challenge...

# multiplatform

[Ryan Simon]

hey all, I'm running into an interesting challenge trying to setup a multi-module multiplatform project.

so my goal is to have one module called :core and one module called :auth . :auth depends on :core.

I also want a Koin setup where :auth and :core Koin dependencies can be initialized on each client app. this would allow me to share a network implementation from each client across both modules

the problem is that when trying to setup the Koin dependencies on iOS, each module has its own version of the Network interface. :auth refers to it as AuthCoreNetwork and :core refers to it as CoreNetwork. with this in mind, we can't properly setup the Network dependency as the interfaces are incompatible

this setup works fine on Android side, but not on iOS.

any idea what I could do to solve for this, if anything? code sample of what I'm trying to do on the iOS side below

func startKoin() {
    NSLog("Hi")
    let doOnStartup = { NSLog("Hello from iOS/Swift!") }
    let network = NetworkManagerImpl()
    
    Core.KoinIosKt.doInitKoinIos(doOnStartup: doOnStartup, network: network)
    Auth.KoinIosKt.doInitKoinIos(doOnStartup: doOnStartup, network: network) // doesn't work because the network instance doesn't match up
}

[xxfast]

ah.. looks like we both are running to the same issue

[xxfast]

I think packForXCode implicitly fix all public api of a module with the name of the module itself - causing this incompatibility

[xxfast]

tried to used some sort of wrapper, but i still run into the same issue - the wrapped type is still scoped to the module

[russhwolf]

If you create multiple Kotlin frameworks, they will have mutually incompatible types. If you need to pass data between different modules, it's better to do so at the Kotlin level and expose just a single top-level framework to iOS.

[Ryan Simon]

gotcha, that's what it seemed like. was hoping there was some trick the community had up its sleeve. alright, not the end of the world

[Ryan Simon]

do you think there's still value in setting up a multi-module project then? feels like it creates more complexity than it's worth dealing with right now at this state of multiplatform @russhwolf

[russhwolf]

yes I think so. Especially as your shared code grows, it can help to give it structure. It's just that the structure is more internal and doesn't get exposed to the Swift layer

[Ryan Simon]

okay that makes sense, thank you. i haven't come across any suggested setups for combining multi-module kmp into a single ios framework. do you have any suggested resources for how to do that?

[russhwolf]

don't know any specific examples off-hand. Generally, the framework config will look the same as for a single module, but that module has some extra dependencies on your other modules. You might need to add export() declarations in your framework if you need to talk to kotlin dependencies from Swift, and/or add transitiveExports = true. The other change is that transitive dependencies will have the module name prefixed when they reach Swift.

[Ryan Simon]

that's helpful info, thank you

[xxfast]

Thanks for the direction @russhwolf 🙂 In my case, i am stuck to multi-modular setup, and I was able to export library dependencies and mark them as api on the lib-module.
:core

sourceSets {
    val commonMain by getting {
      dependencies {
        api(InsertKoin.koinCore)
        ...
      }
    }
}

and
:login

ios {
    binaries {
      framework {
        export(project(":core"))
        baseName = "Login"
      }
    }
}

https://kotlinlang.org/docs/mpp-build-native-binaries.html#export-dependencies-to-binaries

[Ryan Simon]

Nice, doesn't look too bad to setup