Hi Everyone, I have a suspending function in my K...

# coroutines

[khairil.ushan]

Hi Everyone,

I have a suspending function in my KMP module that looks like this

@Throws(
        CancellationException::class,
        UnauthorizedError::class
    )
    suspend fun login() {
        runBlocking {
            val fakeWaitingTime = 300L
            delay(fakeWaitingTime)
        }
    }

Then if I try to execute that login function inside Swift concurrency context like this

Task {
    try? await Auth().login()
}

It will crash with this error:

Function doesn't have or inherit @Throws annotation and thus exception isn't propagated from Kotlin to Objective-C/Swift as NSError.
It is considered unexpected and unhandled instead. Program will be terminated.
Uncaught Kotlin exception: kotlin.native.IncorrectDereferenceException: illegal attempt to access non-shared

I am using this version of coroutines

const val coroutines = "1.6.0-native-mt"

Is there any work around for this? Thank you.

[Joffrey]

runBlocking should not be used inside suspend functions. Why do you need it here?

[khairil.ushan]

That was to silence another error previously 😅

[khairil.ushan]

Initially I don’t use runBlocking, but I got this error on iOS

It is considered unexpected and unhandled instead. Program will be terminated.
Uncaught Kotlin exception: kotlin.IllegalStateException: There is no event loop. Use runBlocking { ... } to

[Joffrey]

Then you should use runBlocking from the most top-level place that calls suspend functions, but not from inside suspend functions themselves

[khairil.ushan]

But the function will be consumed from platform side (iOS, Android, macOS) … I can’t do runBlocking from iOS and macOS. Btw do you think kotlin.native.IncorrectDereferenceException is due to the runBlocking ?

[Joffrey]

I'm not very well versed in Kotlin/Native, but if it's called from platform side, then I think it shouldn't be suspend . You should remove the suspend modifier, and use runBlocking to call suspend functions in a blocking way

[Joffrey]

If you still get the error after that, then I don't know. Maybe you can ask #kotlin-native

[khairil.ushan]

Thanks for your replies 🙏

[Rick Clephas]

Based on the error messages it looks like the non native-mt version is being used. Could you try to force the usage of the native-mt version as described here?

[Rick Clephas]

I’m not very well versed in Kotlin/Native, but if it’s called from platform side, then I think it shouldn’t be suspend . You should remove the suspend modifier, and use runBlocking to call suspend functions in a blocking way

You can actually use suspend functions from ObjC/Swift. These suspend functions are exported to ObjC as completion handler functions. Swift will in turn “import” those as async functions.

Though it’s import to keep in mind that the actual function isn’t a real Swift async function, meaning it doesn’t support cancellation.

If you would like to use suspend functions from Swift, you can take a look at my library KMP-NativeCoroutine which solves the limitations like missing cancellation support.

[Joffrey]

@Rick Clephas TIL, thanks!

[khairil.ushan]

Hi @Rick Clephas thanks for the insight. Will definitely check out your library.
After further investigation, what contribute the issues that I encountered is the way I use Koin in my project. 🤔
So I do the startKoin when SwiftUI app is initialized and inside the onCreate function of my android. Which is happening on main thread.
Then I have component like this

class Authenticator {
  private val store: AuthStore by inject()

  suspend fun login() {}
}

then I try to use it in my Swift code like this

Task {
  do {
    try await Authenticator().login
  } catch {}
}

Since code inside Task is executed NOT in main thread then the error happened.

[Rick Clephas]

Yeah for that to work with the "old memory model" those classes should be frozen.