hey could someone help me with courutine exception casting and handling in swift. I can not manage t...

# ios

[Antonis Radz]

hey could someone help me with courutine exception casting and handling in swift.
I can not manage to cast it in to any Kotlin exception

I have kotlin code:

@Throws(LoginException::class, CancellationException::class, RegistrationException::class)
suspend fun login(email: String, password: String): TSToken {
    throw RegistrationException("Registration exception", "Reg token")
}

and swift code:

SharedDependencies.shared.sessionManager.login(
            email: email,
            password: password,
            completionHandler: { session, error in
               
              if (error is SessionRegistrationException){
                alertErrorText = "Registration exception"
                showingAlert = true
              } else if (error is KotlinException){
                alertErrorText = "Kotlin exception"
                showingAlert = true
              } else{
                alertErrorText = "Unknown exception"
                showingAlert = true
              }
            }
          )

And in debug point I see:

[François]

the error message “No silent login method” doesn’t match with your login method you display.

[François]

Are you sure it call correctly? did you debug your code with the IDE?

[Antonis Radz]

sorry message is random

[Antonis Radz]

yep calling it correctly

[Antonis Radz]

just screenshot is taken later

[Antonis Radz]

it might be related to https://youtrack.jetbrains.com/issue/KT-45127/KMM-hard-to-pass-an-error-to-Kotlin-code-from-implementation-of-Kotlin-method-in-Swift-code

[François]

try debugging with https://github.com/touchlab/xcode-kotlin and see what really happened

[François]

or run debug with the IDE, it needs to be enabled jetbrains://AndroidStudio/settings?name=Advanced+Settings -> “Enable experimental Multiplatform...”

[Antonis Radz]

yep I did that, it is more casting problem, I managed to cast it in to KotlinException, but not in to RegistrationException.
It also could be that I have only reference of SessionRegisrationException,
but in logs it is missing word Shared
*if* (error *is* SessionRegistrationException)

And session is module of kmm project

[François]

try
if (let myError = error as? SessionRegistrationException)

[Antonis Radz]

this is what initially tried

[François]

but yes, I thinks it a issue about casting

[Antonis Radz]

Probably SessionRegistrationException vs RegistrationException, trying with different exception inside shared module so it would not have any prefix

[François]

Or change the way you manage your error management

[Antonis Radz]

yep might need to return result which has error type instead of different exception

[François]

use sealed class with Exception Inheritance

[Antonis Radz]

might also be issue with casting

[Darron Schall]

In your Swift code, you need to do a little digging to get the RegistrationException out.

let exception = error.userInfo["KotlinException"]

if exception is RegistrationException {
  // ...
}

[Antonis Radz]

thank you, already refactored to use sealed class result not exceptions

[François]

@Darron Schall not really developer friendly 😄
I guess extending the KotlinException class on the swift side should be a better approach

[Antonis Radz]

I think my problem was that I was using multi module approach and there is limited visibility of child modules on generated code. Had also some problems with sealed classes casting because inner classes was not generated

[Antonis Radz]

ended up with creating unwrap fun

@OptIn(ExperimentalObjCName::class)
@ObjCName("LoginResult", exact = true)
sealed class LoginResult {
    data class Success(val token: TSToken) : LoginResult()

    data class Registration(val message: String, val token: String) : LoginResult()

    data class Error(val message: String, val statusCode: Int) : LoginResult()

    val tokenSuccess: TSToken? get() = (this as? Success)?.token

    fun unwrap(
        onLoggedIn: (Success) -> Unit,
        onRegistration: (Registration) -> Unit,
        onError: (Error) -> Unit
    ) {
        return when (this) {
            is Success -> onLoggedIn(this)
            is Registration -> onRegistration(this)
            is Error -> onError(this)
        }
    }
}

and

extension LoginResult {
  func handle(promise: Resolver<BaseError>) {
    self.unwrap(
      onLoggedIn: { result in

      },
      onRegistration: { result in

      },
      onError: { result in

      }
    )
  }
}

[François]

did you try to use SKIE enum capabilities ?

[Antonis Radz]

trying to not use third parties as much as possible

[François]

https://skie.touchlab.co/features/sealed

[François]

I see, just it an unavoidable tools

[Antonis Radz]

I have hope that Kotlin in futute improve this kinda stuff 🙂 For now if it does not require to much code I am good with not using third parties

[François]

For exemple, by default, coroutine are not cancellable on the swift side, SKIE (and the another one) fix that issue.

[François]

I also hope Kotlin will improve compatibility

[François]

but SKIE is not mandatory , just make dev life easier 😄

[Antonis Radz]

Oh I need more reading about coroutine are not cancellable on the swift 😄

[François]

https://skie.touchlab.co/features/suspend 😄

[François]

and the another one https://github.com/rickclephas/KMP-NativeCoroutines

[François]

two community approved library

[Antonis Radz]

thank you, definitely will have a look, because I am integrating stuff in to iOS prod app, cheers