Hey all, I have a big upcoming project and I am c...

# multiplatform

[pererikbergman]

Hey all,

I have a big upcoming project and I am considering going KMM so I have been testing, playing learning for the last month or so.

Most of my issues been solve no problem, but I can’t manage to find a solution for this:

I want to be able to wrap any arbitrary library in androidApp and iosApp and inject it into shared, I tried to create a singleton where I would store this wrapper with no success.

In commonMain I want to do this:

object MySingleton {
    var myInterface: MyInterface? = null

    fun hello(msg:String) {
        myInterface?.hello(msg)
    }
}

interface MyInterface {
    fun hello(msg: String)
}

And then in androidApp

MySingleton.myInterface = object : MyInterface {
    override fun hello(msg: String) {
        // do some magic
    }
}

And in iOS something like this:

class MyInterfaceImpl : MyInterface {
    func hello(msg: String) {
        // do some magic
    }
}

 MySingleton.shared.myInterface = MyInterfaceImpl()

But it just crashes on iOS, no clear error message as well.


Anyone have any suggestion on how to do this?

[Trevor Stone]

Have you tried actual/expect

[Trevor Stone]

https://kotlinlang.org/docs/mpp-connect-to-apis.html

[pererikbergman]

I think they have to be in the same module, right ?

[pererikbergman]

I need them to be in different modules.

[Mejdi]

try to add this annotation to the object:
@ThreadLocal
on iOS (KMM) by default all singletons properties are freezed by default..so you cant mutate them. One way to avoid it is to mark it @ThreadLocal which means every thread will get its own copy and will be able to mutate it. Should not be any issue if you dont have multithreading.

[Mejdi]

for reference:
https://kotlinlang.org/docs/kmm-concurrency-overview.html#global-state

[pererikbergman]

It kind of works but it also bet’s the purpose of having a singleton… I don’t want to think what thread it’s coming from… or maybe it’s OK since I use coroutines not threads… 🤔

[Mejdi]

Yes that is my point..due to the limitations with the current multithreading model I hardly see ppl using heavily multiple threads. You will find yourself doing it in very specific cases.
Another option is to use the multi-threading version if coroutines module.

[pererikbergman]

Yeah, I will do some tests