Making calls from C to C# with IL2CPP instead of mono_runtime_invoke

I am trying to figure out how to make calls from C to C# with IL2CPP. For Mono, I would do this by calling mono_runtime_invoke from C using the methods described here: http://www.jerrodputman.com/2010/01/10/the-unityobjective-c-divide

According to the Unity Manual (http://docs.unity3d.com/Manual/iphone-64bit.html):

I know how to make the delegate call to C from C# with DLLImport, but not sure what signature I would have on the C side for the callback and how I would actually make the calls back. Is this even possible yet with IL2CPP or am I stuck using UnitySendMessage?

 

I also tried passing a function pointer as described here:

This gave me the runtime error on IL2CPP:
NotSupportedException: To marshal a manged method, please add an attribute named 'MonoPInvokeCallback' to the method definition

and built with Mono:
ExecutionEngineException: Attempting to JIT compile method '(wrapper native-to-managed)

So I am assuming this method never worked since JIT compiling is not supported on iOS. Question is, what's left?

 

Thanks for the help. Just using MonoPInvokeCallback alone gave me compiler errors but I managed to get it working like this:

C#:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. using System.Runtime.InteropServices;
4. using AOT;
5.  
6. public class Test : MonoBehaviour
7. {
8.     public delegate void TestDelegate();
9.  
10.     [DllImport("__Internal")]
11.     public static extern void _UnmanagedTest(TestDelegate callback);
12.  
13.     [MonoPInvokeCallback(typeof(TestDelegate))]
14.     private static void ManagedTest()
15.     {
16.         Debug.Log("IT WORKS!!!!");
17.     }
18.  
19.     private void Update()
20.     {
21.         if (Input.GetMouseButtonUp(0) == true)
22.         {
23.             _UnmanagedTest(ManagedTest);
24.         }
25.     }
26. }

C++:

Code (CSharp):

1. typedef void (*TestCallback)();
2. extern "C" void _UnmanagedTest(TestCallback testCallback)
3. {
4.     testCallback();
5. }

 

Hi, I have tried to run this code on Unity5.4.0f3 it gave me this error. "IL2CPP does not support marshaling delegates that point to instance methods to native code." Any Idea about that ?

 

Discord rpc stopped working with il2cpp in Unity 2018.2:

https://github.com/discordapp/discord-rpc/issues/243 ($50 Bounty!)

Anyone know how to get this il2cpp working? I tried using the steps above. Their original code looks like this (just listing their Ready func - they have about 5 others):

[UnmanagedFunctionPointer(CallingConvention.Cdecl)]

public delegate void ReadyCallback(ref DiscordUser connectedUser);



public struct EventHandlers

{

    public ReadyCallback readyCallback;

}



// I believe ReadyCallback triggers after this, but just a guess

[DllImport("discord-rpc", EntryPoint = "Discord_Initialize", CallingConvention = CallingConvention.Cdecl)]

public static extern void Initialize(string applicationId, ref EventHandlers handlers, bool autoRegister, string optionalSteamId);

I've been doing some trial-and-error attempts, but no dice.

 

Doh, I gave the closed ticket link -- here is the thread revival one -- I'll port your comment. Thanks for that!

I have been trying to implement the original linked solution that you saw to no success. It's probably 1 small thing I'm doing wrong.

There's a $50 bounty if you toss up a working template to this new link:

https://github.com/discordapp/discord-rpc/issues/243

If you scroll to the bottom, you can see what I attempted to no avail. It may just need 1 or 2 changes! I know it's 3rd party, but you'll be helping tons of Unity il2cpp porters that use or want to use Discord rich presence features ;D

 

I have issues with unicode strings in delegate callbacks. Any way to control the marshalling of that?

 

Strange. I use the code on many platforms but on Unity Android il2cpp i only get a callback with one character. Typically a situation when a unicode string is interpreted as ansic C

 

Code (CSharp):

1.  
2. [UnmanagedFunctionPointer(CallingConvention.Cdecl, CharSet = CharSet.Unicode)]
3. public delegate void EventHandler_OnMessage(string sender ,MessageLevel level, string message);
4.  

and

Code (CSharp):

1.  
2. [MonoPInvokeCallback(typeof(EventHandler_OnMessage))]
3. private static void MessageHandler(string sender, MessageLevel level, string message)
4. {
5.      OnMessage?.Invoke(sender, level, message);
6. }
7.  

On Unity 2019.2.12 Android i get ansi C marshall in MessageHandler that are called with wide unicode strings

 

How. Can you explain more. The same code works in mono and Windows

 

https://docs.microsoft.com/en-us/do...unctionpointerattribute?view=netframework-4.8

Doesnt this apply?

 

Thanx! Just thought IL2CPP should work like mono and MS C#

 

Actually it doesnt seem to work anyway :-( even if I add your attributes with IL2CPP

 

It creates a utf8 string from the sent unicode utf16 instead of constructing it from unicode and stops generation as the first char is taken and the second is a zero so it ends up with a one character string

 

Filed a demo to the bug reporter

 

Still no resolution in 2019.2.17

Attached a pdf that shows the problem

 

Case 1201898 submitted 29/11 2019

 

Still no solution in 2019.3.1f1 and the issue 1201898 is removed ?

 

Great ! Thanx !

Meanwhile i have changed to use ansi as string encoding so it works but IL2CPP should work as other C# implementations

 

This really helped me thanks....