Hi everyone! I was wondering how you implement li...

# multiplatform

[Anton Afanasev]

Hi everyone!

I was wondering how you implement listeners in KMM ( in particular K\N)? To avoid retain cycles?
Do you use expect/actual and wrap listener with WeakReference on K\N?

For example:

// Multiplatform
class KmmLibrary(private val listener: Listener) {

    fun doSomething() {
        listener.notifyResult("All good!")
    }

    interface Listener {
        fun notifyResult(result: String)
    }
}

// Native
struct ContentView: View {
    @State private var message: String = ""
    private let kmmLibrary: KmmLibrary

    init() {
        self.kmmLibrary = KmmLibrary(listener: NativeListener())
    }

    class NativeListener: Listener {
        func notifyResult(result: String) {
            print(result)
        }
    }
}

Does not this code created retain cycle on iOS (Native)?
Should I somehow wrap it with WeakReference using expect/actual mechanism or are there any other common practices?

[Andrey Chernov]

Yes, you should wrap link to listener in WeakReference. We use it in events dispatcher https://github.com/icerockdev/moko-mvvm/blob/master/mvvm-core/src/iosMain/kotlin/dev/icerock/moko/mvvm/dispatcher/EventsDispatcher.kt

[Anton Afanasev]

Thats more or less I was thinking about!
Большое спасибо за инфу.