Wrapper Classes should be frozen on create

If we freeze the wrapper classes after creation, we can then safely pass those around between iOS threads.

Simple example in pseudo swift code:

this will work as both the creation and the call happen on the main thread

THREAD:MAIN {
   let loadUserUseCaseIos = LoadUserUseCaseIos(LoadUserUseCase(...))
  
   loadUserUseCaseIos.loadUser(username: "foo").subscribe(
              scope: coroutineScope, //this can be provided automatically, more on that below
              onSuccess: { user in print(user?.description() ?? "none") },
              onThrow: { error in print(error.description())}
          )
}

this will FAIL as the creation happens on another thread than the call

THREAD:MAIN {
   let loadUserUseCaseIos = LoadUserUseCaseIos(LoadUserUseCase(...))
}
THREAD:IO {
   loadUserUseCaseIos.loadUser(username: "foo").subscribe(
              scope: coroutineScope, //this can be provided automatically, more on that below
              onSuccess: { user in print(user?.description() ?? "none") },
              onThrow: { error in print(error.description())}
          )
}

But if we freeze the LoadUserUseCaseIos after creation, both will work fine. https://kotlinlang.org/docs/mobile/concurrency-overview.html#immutable-and-frozen-state

[micHar]

Fixed in 0.6.0 via #33.

The samples can be found here:

• shared: https://github.com/FutureMind/koru-example/blob/master/shared/src/commonMain/kotlin/com/example/multiplatform/koru/shared/abstractexamples/MutableVsFreezeExample.kt
• ios: https://github.com/FutureMind/koru-example/blob/master/iosApp/iosApp/SceneDelegate.swift#L28

[JohNan]

I just looked through the repo by @russhwolf and he created 4 wrappers to be able to handle nullable and non-null data. I still think this is a good idea and would make the swift side of the code easier to work with. At least it would be up to the consumer of the library to choose and not forced.

https://github.com/touchlab/SwiftCoroutines