Unable to use uwp plugin windows minimum version 16299

Unity version# 2019.4.8f1

We have a need to use a c# UWP dll with windows minimum target set as 16299 and use the type that derives from the System.IO.Stream type. There are two issues with this. Firstly, while copying the plugin within Unity, got the error as below. I believe this error is due to the System.IO.Stream type which is moved to System.Runtime.dll for windows build#16299. For lower windows builds, this type is present in System.IO.dll itself and has no issues. Only starting from 16299 build, this error throws.



I just ignored this error and tried building the project in Unity for UWP platform. Then I got the error as attached below. It throws up the System.Runtime error and unable to build the project. I tried setting the API Compatibility Level to both .Net 4.x and .net standard 2.0, but no luck.
Can you let me know how to use a uwp plugin with 16299 min version?

I've also created the bug # 1277945.

 

There's one catch - we are unable to set this target to 5.4.4 as we're using .NET standard 2.0 dll reference to this uwp plugin. And it's not just one dll, there are many bunch of .net standard 2.0 dll's are been referred by this UWP plugin and the versions cannot be lowered.

What could be the way forward for this problem?

 

We're already using IL2CPP backend as using Unity 2019.4. The actual problem I'm mentioning is, we have third party uwp DLLs that in turn use UWP target version 6.x because that plugin uses other .net standard 2.0 DLLs.

We've no source access to uwp plugin as it's external.

 

Not possible to compile as .net standard 2.0 because it requires uwp functionalities and it's quite big application which interfaces with hardware.

And we're developing application for hololens2, so we need to refer those hardware interfacing functionalities to use it in hololens2.

 

Hi @Tautvydas-Zilys

Is there a way to call UWP API from .NET Standard 2.0 library? I tried the following code in a class library project but does not seem to work. Unable to resolve type EasClientDeviceInformation. Following are the project details:

.csproj
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>netstandard2.0</TargetFramework>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Microsoft.NETCore.UniversalWindowsPlatform">
<Version>5.4.4</Version>
</PackageReference>
</ItemGroup>
</Project>

Class1.cs
using System;
namespace ClassLibrary1
{
public class Class1
{
void test()
{
var easClientDeviceInformation = new Windows.Security.ExchangeActiveSyncProvisioning.EasClientDeviceInformation();
}
}
}

 

Referring the winmd, made the solution to compile.

But now the issue with referring that compiled assembly back to Unity (2019.4.22f1). I'm getting the following error while building the UWP player. I've copied both dll & winmd into assets folder. Checked with API scripting compatibility set to both .NET 4.x or .NET Standard 2.0. The same issue occurs. Any addition settings or files need to be copied to made it work?

Assets\Test.cs(9,20): error CS7069: Reference to type 'EasClientDeviceInformation' claims it is defined in 'Windows.Security.ExchangeActiveSyncProvisioning.EasContract', but it could not be found

Test.cs:

using UnityEngine;

public class Test : MonoBehaviour
{
// Start is called before the first frame update
void Start()
{
#if ENABLE_WINMD_SUPPORT
var info = TestLib.UwpHelper.GetDeviceInfo();
Debug.Log(info);
#endif
}
}

 

Copied from here: C:\Program Files (x86)\Windows Kits\10\UnionMetadata\10.0.18362.0\Windows.winmd as it's the same reference which is given in the class library plugin.

Attached screenshot of plugin inspectors for both dll & winmd files

 

The error is still the same with/without the Windows.winmd file. Attached the projects for reference. Let me know if I'm missing anything please.