Send id<MTLTexture> from ios to unity

Question

I'm writing a plugin for unity, I need to send a texture from ios to unity. There is a UnitySendMessage function which takes char* as parameter, but I didn't find a way to convert id<MTLTexture> to char*.

How can I send id<MTLTexture> from ios and receive it in unity?

My current code :

//ios side ...
_texture = CVMetalTextureGetTexture(texture);
UnitySendMessage(CALLBACK_OBJECT, CALLBACK_TEXTURE_READY,_texture);//error
//...

//unity side
private void OnTextureReady(string texture_str)
{
   IntPtr texture = new IntPtr(Int32.Parse(texture_str));
   int width = 256;
   int height = 256;
   rawImage.texture = Texture2D.CreateExternalTexture(width, height, 
   TextureFormat.ARGB32, false, false, texture);
}

Answer 1

Don't try to cast string to IntPtr. char* is just pointer and any pointer(char*, void*,...) coming from native side unity treat it as IntPtr.

id<MTLTexture> tex = yourTexture;
char* ptr = &tex;

And now you have a ptr from native side