How do you include pre-compiled .NET DLLs in Unity

Question

miserable assembly reference

Unity is having trouble finding my DLL. I have a DLL that I'm able to successfully load in visual studio by adding a reference, but I'm still getting errors in Unity.

The DLL is in .NETframework 4.6.1, and I've tried upgrading the unity .NETframework to 4.x, installing the relevant SDK in the visual studio installer, using different versions of unity (2022, 2020, 2019), all no good.

I know the DLL works because I've been able to compile it outside of unity, but my goal for this project is to have it running in unity without hacky IPC.

Here are a few references to other things I've tried that don't work: A reference to the dll could not be added .dll file not accessible https://answers.unity.com/questions/458300/how-to-use-a-external-dll.html

edit1: So I've tried arranging the DLL as described, but that doesn't solve the issue. I think it must be an issue of "compatible binary" is there an easy way to check that?

more details: the DLL I'm having trouble referencing is a wrapper for another DLL, translating between C# and C++, might that be the issue?

please save me stack overflow.

DLLs in the project, .net DLL referencing c++ DLL

Answer 1

To use plugins/pre-compiled assemblies in Unity (native or .NET), you must place the .DLL(s) in the Assets/Plugins folder. You can use child folders for x86 ir x64. I like to include a vendor name too. Tell me more....

e.g.

Assets
|--Plugins
   |--MickyD
      |--MickyD.SoM.Contracts.dll

Assuming it is a compatible binary, Unity will make the contents of the plug-in available to scripts that you define in Unity.

All you need do is to add the appropriate using at the top of your Unity script.

e.g.

using MickyD.SoM.Contracts;
using UnityEngine;
.
.
.
namespace MickyD.FleetDefender.Vehicles
{
    public class PlaneGadget
    {
        private Airspeed _airspeed; // Type defined in pre-compiled assembly
    }
}

If you are using ASMDEFs in your project with overridden includes then you might need to reference the DLL.

See also

• Import and configure plug-ins

Answer 2

This is a small case of Unity's C# script compiling dll. Hope it helps you.

Unity's C# script compiles dll.

First create a DllTest scene.

Create a C# script that will be compiled into a dll, named TestLog, and add a method printout to judge whether the method is successfully called. If it is successful, the console will output "Call TestLog succeeded".

  public void ShirlLog()
  {
      UnityEngine.Debug.Log("TestLog was called successfully")
  }

Create a Text script to test the success of calling the dll.

   public class Test : MonoBehaviour
 {
     private TestLog t;

     void Start()
   {
     //  Add TestLog script component
      t = GameObject.FInd("Main Camera").GetComponent<TestLog>();
      if(t == null)
      {
         t = GameObject.FInd("Main Camera").AddComponent<TestLog>();
      }
      // Call the ShirlLog method of the TestLog script
      TestLog l = new TestLog();
      l.ShirlLog();
   }

 }

Mount the Text script for the camera

The preparations are completed, and then the dll file is compiled.

Click to generate an .asmdef file, change it to the name you want, and change it to TestLog here. At this time, the dll file will be generated in the following directory.

Cut the file under Plugins.

Delete the C# script compiled into dll and prepare for testing

Running the project found that the TestLog script was automatically mounted on the Main Camera object; the ShirlLog of the TestLog script was successfully called, and the output "TestLog was called successfully" was output.

That's because the Test script provides two tests.

The first is to test mount the C# script in the dll to the game object:

 private TestLog t;
 t = GameObject.Find("Main Camera").GetComponent<TestLog>();
 if(t == null)
 {
     t = GameObject.Find("Main Camera").AddComponent<TestLog>();
 }

The second test is to test the success of calling a method in a class compiled into a dll.

 private TestLog t;
 TestLog l = new TestLog();
 l.ShirlLog();