Hi, I’m using ViewModel to manage global states, it works with Android but throws an exception with ...

# multiplatform

[Phuc]

Hi, I’m using ViewModel to manage global states, it works with Android but throws an exception with iOS.

Uncaught Kotlin exception: kotlin.UnsupportedOperationException: `Factory.create(String, CreationExtras)` is not implemented. You may need to override the method and provide a custom implementation. Note that using `Factory.create(String)` is not supported and considered an error.

[Phuc]

I also tried this https://www.jetbrains.com/help/kotlin-multiplatform-dev/compose-viewmodel.html#adding-the-common-viewmodel-to-your-project

[Phuc]

But got the same exception

[Pablichjenkov]

I believe you have to use the overload that takes an initialize {} lambda

[Phuc]

fun MyComposable(viewModel: MyViewModel = viewModel { MyViewModel() })

like this right? I just changed to this and it is working now

[Phuc]

This one didn’t work

fun MyComposable(viewModel: MyViewModel = viewModel())

[Phuc]

But I don’t really understand why it works 🙂

[Pablichjenkov]

Far from the Mac right now but in general the viewModel() function doesn't know how to create your ViewModel unless you tell it how to, with the initializer parameter.
You can use koin in the meantime. It has support for that already.

[Phuc]

It’s strange for me that it works on Android, but not iOS

[Phuc]

and it does not show any error in compile time

[Phuc]

Let me check what Koin is, thanks @Pablichjenkov

[Pablichjenkov]

It should have a better error message right but is very fresh. In the docs you linked it explains in the bottom that, in JVM it is possible to instantiate a ViewModel class that has no constructor parameters using reflection. But outside JVM this is not possible.
Koin is a DI library, it offers first class support for compose multiplatform, worth checking