I'm trying to use Ktor on iOS through a Kotin Multiplatform project. But I keep getting

kotlin.native.concurrent.InvalidMutabilityException: mutation attempt of frozen

error when i'm using on iOS ( the android part work well BTW ) I've defined a specific dispatcher for iOS like this :

internal val ApplicationDispatcher: CoroutineDispatcher = NsQueueDispatcher(dispatch_get_main_queue())

internal class NsQueueDispatcher(
    private val dispatchQueue: dispatch_queue_t
) : CoroutineDispatcher() {
    override fun dispatch(context: CoroutineContext, block: Runnable) {
        dispatch_async(dispatchQueue) {
            block.run()
        }
    }
}

And I use like this in a presenter that I will connect to the iOS UIViewController

class ExampleViewPresenter : BasePresenter() {

   fun test() {
        launch {
            try {
                val example =  ExampleSuspendMethod() 

                withContext(Main) {
                    println(example)
                }

            } catch (e: Throwable) {
                println(e)
            }
        }
}

I've defined the scope of

launch

in BasePresenter like this:

abstract class BasePresenter : CoroutineScope {

    private var job = Job()

    override val coroutineContext: CoroutineContext
        get() = ApplicationDispatcher + job

    fun onDestroy() {
        job.cancel()
    }

}

I've found people with the same error on stack overflow and on this channel but the cause was a bug in Kotlin

1.3.11

and I'm using

1.3.21

. I've found one similar project with the same version of Kotlin but I didn't succeed to make it work ( https://github.com/watabee/RakutenRankingKotlin ) Did anyone succeed to use Ktor client on iOS with Kotlin

1.3.21

?

Please note that coroutines is not supported between multiple threads. What is

Main

dispatcher in your code?

Thanks ! I will take a look to the example.

Main

is not useful, old test code…

I’m having a similar issue. I’ve basically tried to get as much as I can from the KotlinConf app as I can but I’ve hit a brick wall. My code is open source so you can poke it with a stick if you want: https://github.com/bakkenbaeck/porchpirateprotector

Is your HttpClient a property of a singleton (

object

) ?

@gonzooin yes, it is!

We’re experimenting right now, but it may be the cause

interesting! I’ll poke at that and see what i come up with

Yeah this was the issue. It still doesn’t work but because of the next error in line. Don’t store an

HttpClient

instance inside an

object

@ribesg @gonzooin I got it working! a big piece of it was the fact that it was on an

object

, so thank you

Congrats on that 👏 We figured out by keeping a reference to httpClient from Swift ( for summarize the solution 😄 )

Awesome thanks for the investigation, probably I have an idea how to fix the issue with client in object and try to implement it in next release 🙂