hey any ideas how to achieve kotlin data class wit...

# multiplatform

[Antonis Radz]

hey any ideas how to achieve kotlin data class with default arguments like

data class TestViewState(
    val list: List<Test> = emptyList(),
    val stateText: String = ""
)

so on XCode it would have default empty constructor?

like

@State private var viewState: TestViewState = TestViewState()

Currently it is not working because of XCode error : 'init()' is unavailable
It does work as long as it is initialised with values

Sorry I am Android dev, not iOS 🙂 (edited)

Also made it happen with adding getter to companion object, but this is a hack not a solution

[Vitaliy Zarubin]

I answered here
https://kotlinlang.slack.com/archives/C0B8M7BUY/p1666436627010159?thread_ts=1666435668.224729&cid=C0B8M7BUY
It's just a language, not really related to multiplatform.

[Antonis Radz]

yep, sorry, that was wrong channel. You answered with swift code, but what I need is kotlin data class usage on swift, not creating swift class

[Vojtěch Pešek]

As far as I know, default arguments (wheter it is methods or constructors) are not available in objC. Either you explicitly pass them from iOS, you create secondary constructor or you could do a wrapper in iosMain

[saket]

I'm unable to find it right now but there is a youtrack for this

[Antonis Radz]

I did workaround like this:

data class TestViewState(
    val list: List<Test> = emptyList(),
    val stateText: String = ""
) {
    
    companion object {
        val initialise get() = TestViewState()
    }
}

and in swift

@State private var viewState: TestViewState = TestViewState.Companion().initialise

[Duane Malcolm]

I find this annoying. I fix this by replicating the constructor:

data class TestViewState(
    val list: List<NavEvent.Test> = emptyList(),
    val stateText: String = ""
) {
    
    constructor() : this(
        list = emptyList(),
        stateText = ""
    )
}

[Antonis Radz]

replicating constructor looks better, thanks

[Darron Schall]

The YouTrack issue for this is https://youtrack.jetbrains.com/issue/KT-38685

[svyatoslav.scherbina]

Btw, there is no need to specify all the arguments when replicating the constructor. Something like

constructor() : this(list = emptyList())

should be enough.