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kotlinlang

Hey guy, how do share viewmodels in KMM? Knowing that Android view models have lifecycle dependent on the platform?

I did this through expect/actual.

in commonMain, declare an _expect_, eg CommonViewModel (with maybe a few expect funs as well).

In androidMain, _actual_ this with an Android ViewModel (and possibly some _actuals_ for these funs as well).

In iOS Main, just a plain class for the _actual_ (with some _actuals_ for these funs as well).

<@U72C3TBDH> Okay thanks. Will interface make sense in this context? Does actual/expect have an advantage?

I favor interfaces&amp;implementations. But for me actua/expect worked better for ViewModel, since you can have a different/separate class hierarchy, not requiring a single (top) interface.

Eg, on Android, I could do `actual class KmpViewModel : ViewModel() { .....}` and on iOS `actual class KmpViewModel { ... }` and create them (not having them injected) in my native Android or iOS code.

More detailed:
commonMain:
```/**
 * A [ViewModel] expects to be implemented by a platform specific
 * implementation of a View-Model.
 */
expect abstract class ViewModel() {
    /**
     * This method must be called when this [ViewModel] is no longer needed.
     * It cleans up its resources and cancels its scope.
     */
    abstract fun onDestroy()
}

...
...

abstract class BaseViewModel(protected val scope: CoroutineScope, protected val log: Kermit): ViewModel() {
    override fun onDestroy() {
        log.v { "onDestroy called" }
        scope.cancel()
    }
    ...
}```
androidMain:
```/**
 * Android implements the [ViewModel] through its Android lifecycle [androidx.lifecycle.ViewModel].
 */
actual abstract class ViewModel : androidx.lifecycle.ViewModel() {
    override fun onCleared() = onDestroy()

    actual abstract fun onDestroy()
}```
iosMain:
```/**
 * iOS does not provide any platform-specific implementation for a [ViewModel].
 */
actual abstract class ViewModel {
    actual abstract fun onDestroy()
}```