I came across an article talking about the concurrency model and it talks about freeze(). I tried to...

# multiplatform

[Rak]

I came across an article talking about the concurrency model and it talks about freeze(). I tried to run the code but the IDE does not recognise the freeze() method. What am I doing wrong? https://play.kotlinlang.org/hands-on/Kotlin%20Native%20Concurrency/02_Frozen

[Tiago Nunes]

freeze is only available in native source sets (e.g. iosMain)

[Rak]

My project is refusing to work with iOS, do you know if I create Kotlin code that “breaks the rules” in some way to do with mutable state, it will crash iOS?

[Rak]

even if I don’t reference those classes in iOS?

[Tiago Nunes]

Hm if you don't reference it in iOS it shouldn't be a problem. Illegal mutable state sharing only results in runtime crashes at the time it's invoked

[Rak]

any resources for writing the kotlin code in such a way as to not hit the “rules”?

[Tiago Nunes]

Kevin Galligan's talk on KotlinConf 2019

https://youtu.be/oxQ6e1VeH4M▾

. I think that codelab you're seeing is a resource from this talk

[Rak]

I followed some jetbrain tutorial a showing how to make a network request

[Rak]

it worked but when i tried to write my own code to do something similar it worked fine on android but i got errors in iOS

[Rak]

doesn’t help that my iOS knowldesge is zero

[Tiago Nunes]

I don't know much either, thankfully my collegues can help me

[Tiago Nunes]

What were these errors? Maybe I can help

[Rak]

that would be great, give me a sec

[Rak]

06-17 120230.018 💜 VERBOSE HTTP Client - RESPONSE https://gitcdn.link/cdn/KaterinaPetrova/greeting/7d47a42fc8d28820387ac7f4aaf36d69e434adc1/greetings.json failed with exception: kotlin.native.concurrent.InvalidMutabilityException: mutation attempt of frozen kotlin.collections.HashMap@cc0428

[Tiago Nunes]

You're using Ktor?

[Rak]

here’s the source code for the shared kotlin code being called from iOS

[Rak]

https://github.com/KaterinaPetrova/kmm-ktor-sample/blob/master/shared/src/commonMain/kotlin/com/jetbrains/kmmktor2/Greeting.kt

[Rak]

whats strange is that this all worked at one point

[Rak]

I started adding more kotlin code and tested on android

[Rak]

all worked but whn i tried on iOS i got these errors, even when i stopped refrencing my code and went back to the sample

[Rak]

yes Ktor

[Rak]

i just checked out the sample project from github (my initial project was written manually)

[Tiago Nunes]

Might be a problem with your dependencies

[Tiago Nunes]

[Tiago Nunes]

https://kotlinlang.org/docs/mobile/concurrency-and-coroutines.html#multithreaded-coroutines

[Rak]

hmm, but KMM can use coroutines

[Rak]

and the sample did work

[Tiago Nunes]

Are you using any libraries that the sample doesn't use?

[Rak]

i added kotlinx serialisation

[Rak]

I’m going to build my app bit by bit and see when it started to fail

[Tiago Nunes]

Try adding this to commonMain:

implementation ("org.jetbrains.kotlinx:kotlinx-coroutines-core"){
    version {
        strictly("1.5.0-native-mt")
    }
}

[Rak]

so commonMain has no depndecy on coroutines

[Rak]

but the androidTest section has implementation(“org.jetbrains.kotlinxkotlinx coroutines test1.5.0”)

[Rak]

the android app has a dependency to:

[Rak]

implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutinesVersion")

[Tiago Nunes]

Try using the mt version

[Rak]

but when i add what you suggested to commonMain

[Rak]

Cannot find a version of ‘org.jetbrains.kotlinx:kotlinx-coroutines-core’ that satisfies the version constraints:
Dependency path ‘PocKMMandroidAppPocunspecified’ --> ‘org.jetbrains.kotlinxkotlinx coroutines core1.5.0’

[Tiago Nunes]

When using other libraries that also depend on kotlinx.coroutines, such as Ktor, make sure to specify the multithreaded version of kotlinx-coroutines

[Rak]

where did you get that from?

[Tiago Nunes]

https://kotlinlang.org/docs/mobile/concurrency-and-coroutines.html#multithreaded-coroutines

[Rak]

thanks!

[Tiago Nunes]

Did it solve your problem?

[Rak]

unfortunately not

[Rak]

but thanks anyway