Pass Lambda function to C# generated code of Kotlin in Xamarin.Android binding library

Question

I've been trying to use my Android Library (written in Kotlin) in a Xamarin project but I'm stuck in passing Lambda functions to C# generated code of Kotlin

I'm trying to do something like this

client.DoSomething((response) => {}, (error) => {});

But I'm getting this error

CS1660: Cannot convert lambda expression to type 'IFunction1' because it is not a delegate type

This is the generated C# code for my library for this specific function

using Android.Runtime;
using Java.Interop;
using Java.Lang;
using Kotlin.Jvm.Functions;
using System;
[Register ("doSomething", "(Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)V", "")]
public unsafe void DoSomething (IFunction1 onSuccess, IFunction1 onFailure);

What's the correct way of doing this?

Answer 1

I'm using this class in order to adapt the Function1 exported by a Kotlin Binding to C# Lambda:

class Function1Impl<T> : Java.Lang.Object, IFunction1 where T : Java.Lang.Object
{
    private readonly Action<T> OnInvoked;

    public Function1Impl(Action<T> onInvoked)
    {
        this.OnInvoked = onInvoked;
    }

    public Java.Lang.Object Invoke(Java.Lang.Object objParameter)
    {
        try
        {
            T parameter = (T)objParameter;
            OnInvoked?.Invoke(parameter);
            return null;
        }
        catch (Exception ex)
        {
            // Exception handling, if needed
        }
    }
}

Using this class you would be able to do the following:

client.DoSomething(new Function1Impl<ResponseType>((response) => {}), new Function1Impl<ErrorType>((error) => {}));

P.S.: ResponseType is the class of your input param response and ErrorType is the class of your input param error.