I have a multiplatform Android / iOS app and want ...

# ktor

[Lukasz Kalnik]

I have a multiplatform Android / iOS app and want to use on Android OkHttp with custom DNS implementation. The Ktor HttpClient is declared in the shared multiplatform part. How can I inject OkHttp with the custom DNS into the shared part only for Android?

[simon.vergauwen]

My personal choice would be to create an expect fun createEngine(): HttpClientEngineFactory<T> and return the OkHttp version from Android configured with your custom DSN, and the darwin version on iOS.

HttpClient(createEngine())

[simon.vergauwen]

If you're using DI like Koin, you can alternatively also use that.

[Lukasz Kalnik]

What is T in this case?

[simon.vergauwen]

Ah, it's the type of the config specific to the engine used. So in my case with Apache. data object Apache : HttpClientEngineFactory<ApacheEngineConfig>.

For data object OkHttp : HttpClientEngineFactory<OkHttpConfig> which gives you access to the underlying client for example. Reference: OkHttpConfig API Docs

[simon.vergauwen]

So you can configure:

val client: HttpClient = HttpClient(OkHttp) {
  // configure OkHttp
}

[Lukasz Kalnik]

Ok, thank you for the suggestion!

[simon.vergauwen]

I'm sorry, I made a mistake 😅 You need to share a preconfigured client engine.

expect fun createEngine(): HttpClientEngine

actual fun createEngine(): HttpClientEngine =
   OkHttp.create {
     // configure
   }

[Lukasz Kalnik]

Thank you, that worked perfectly and was actually very simple, once you wrap your mind around how expect/actual work 🙂