iOS example not working correctly, throws: mutation attempt of frozen kotlin.collections.HashMap

[falcon4ever]

Hi,

I was following the tutorial Kotlin Multiplatform Hands-on: Networking and Data Storage from scratch using Android Studio Arctic Fox Beta 4 and KMM plugin v0.2.6.

The Android demo works great, the iOS demo seems to have a problem trying to retrieve the data from the shared KMM module.

I also noticed that the iOS template that's generated with KMM plugin v0.2.6 is different from the one in the tutorial and this repo. The plugin now generates a template with iOSApp.swift and ContentView.swift only (there is no AppDelegate.swift or SceneDelegate). In my fork I made some changes to make it run, unfortunately, it gives me the following error when launching: "mutation attempt of frozen kotlin.collections.HashMap@1cad628"

Steps to replicate:

• Clone my fork: https://github.com/falcon4ever/kmm-networking-and-data-storage/tree/final-AndroidStudio_ArcticFoxBeta4-KMM_v0.2.6
• in the iosApp folder, run pod install / pod update before opening the xcode project (or building/running the iOS project from Android Studio)

Any ideas how to fix the demo code?

I'm using:

• Kotlin: 1.5.20
• Coroutines: 1.5.0-native-mt
• Serialization: 1.2.1
• ktor: 1.6.0
• sqldelight: 1.5.0

edit June 30th 2021
I also tried updated the existing final branch to see if it was some XCode proj issue (but it gives the same result):

• https://github.com/falcon4ever/kmm-networking-and-data-storage/tree/final-patched-AndroidStudio_ArcticFoxBeta4
• falcon4ever@10f4644

[falcon4ever]

Ok, figured it out and it's related to the serialization library:

• https://twitter.com/joreilly/status/1412701348638900227
• kotlin.native.concurrent.InvalidMutabilityException: mutation attempt of frozen kotlin.collections.HashMap Kotlin/kotlinx.serialization#1450

If you add useAlternativeNames = false in SpaceXApi.kt the iOS app will work correctly:

class SpaceXApi {
    private val httpClient = HttpClient {
        install(JsonFeature) {
            val json = Json {
                ignoreUnknownKeys = true
                useAlternativeNames = false
            }
            serializer = KotlinxSerializer(json)
        }
    }

[KaterinaPetrova]

Hey @falcon4ever, thanks for reporting it. I've updated the sample (added a workaround). The final branch was forced-pushed (to keep the clean history, which represents the steps of the tutorial)