I tried something as bellow. In the common module ...

# kotlin-native

[Cyrille QUÉMIN]

I tried something as bellow. In the common module I have:

interface View{
  suspend fun myFunSuspend().
}

// for Android, normal implementation of co routine
// for iOS see below, because I need to call a function in swift that uses callbacks

class iOSViewWrapper(private val iOSImpl: IosView) : View {

  override suspend fun myFunSuspend(){
    return suspendCoroutine {
      iOSImpl.doAsyncJob{ data, error ->
        if(error != null){
          it.resumeWithException(error)
        }else{
          it.resume(data)
        }
      }
    } 
  }
}

interface IosView {
  fun doAsyncJob((data: ByteArray, error: Throwable?)-> Unit)
}

the function doAsyncJob implementation is done in Swift and is called many times inside my kotlin code.
I have defined a coroutine scope that is using the ios dispatch_get_main_queue.
I have made sure that doAsyncJob is execute AND invoke the closure on the main thread.

The code works but crashes always in the swift invocation of the closure.
Sometimes after 1 call sometimes after 6 or 10, ...
I tried to declare the closure of doAsyncJob as a variable and call .freeze() on it, but I get

kotlinx.coroutines.CoroutinesInternalError: Fatal exception in coroutines machinery for DispatchedContinuation[MainDispatcher@7d793018, Continuation @ $prepareCOROUTINE$11]. Please read KDoc to 'handleFatalException' method and report this incident to maintainers
        at 0   mylib                            0x0000000100f81e98 kfun:kotlin.Error.<init>(kotlin.String?;kotlin.Throwable?)kotlin.Error + 24
        at 1   mylib                            0x0000000100f81bc0 kfun:kotlinx.coroutines.CoroutinesInternalError.<init>(kotlin.String;kotlin.Throwable)kotlinx.coroutines.CoroutinesInternalError + 24
        at 2   mylib                            0x0000000100f81818 kfun:kotlinx.coroutines.DispatchedTask.handleFatalException$kotlinx-coroutines-core(kotlin.Throwable?;kotlin.Throwable?) + 284
        at 3   mylib                            0x0000000100f82540 kfun:kotlinx.coroutines.DispatchedTask.run() + 1224

what am I doing wrong?
I am using kotlin 1.3.41 and coroutine 1.3.0-RC with an mpp project android and ios

[kpgalligan]

You get the CoroutinesInternalError on freeze only? What is the crash you get otherwise?

[Cyrille QUÉMIN]

yes, the crash I get otherwise is BAD_ACCESS on the swift side

[Cyrille QUÉMIN]

the only workaround I have just found is instead of declaring the closure inline in swift, I assign them to a class variable, pretty ugly codewise but it works….
instead of this that looks neater but crashes:

public func connect(completionHandler: @escaping (Error?) -> Void) {
  session?.connect(to: url!) { (error: Error?) in
    completionHandler(error)
  }
}

I had to do something like that:

private var chConnect: ((Error?) -> Void)? = nil
public func connect(completionHandler: @escaping (Error?) -> Void) {
    chConnect = completionHandler
    session?.connect(to: url!, completionHandler: handleConnection(error:))
}

private func handleConnection(error: Error?){
  chConnect?(error)
}

[svyatoslav.scherbina]

Please avoid cross-posting: https://kotlinlang.slack.com/archives/C3SGXARS6/p1565303785199900?thread_ts=1557146138.153600&cid=C3SGXARS6

See also my answer there.