Xamarin.iOS项目：CS1703：已导入具有相同标识的多个程序集 [英] Xamarin.iOS project: CS1703: Multiple assemblies with equivalent identity have been imported

问题描述

我有一个使用.NET Standard 2.0的跨平台（iOS和Android）Xamarin解决方案。该解决方案由Visual Studio 2017构建（我已经尝试了当前版本和预览版本）。 Forms和Android项目构建良好。但是，iOS无法构建，并出现以下错误：

1> CSC：错误CS1703：已导入多个具有相同标识的程序集：'C：\Users \newuser.nuget\软件包\system.reflection.emit\4.3.0\ref\netstandard1.1\System.Reflection.Emit.dll'和'C：\Program Files（x86）＼ Microsoft Visual Studio预览版企业 Common7 IDE参考程序集 Microsoft框架 Xamarin.iOS v1.0外观 System.Reflection.Emit.dll。删除重复的引用之一。

我已经尝试过许多解决方法，如下所述：

在我看来，问题（如错误所示）是由Visual Studio安装的System.Reflection.Emit的旧版本。但是，我找不到忽略它的方法，而是使用System.Reflection.Emit版本。如上文所述，我尝试在Xamarin.iOS项目中使用project.json文件，并手动忽略，但这不起作用。

顺便说一句，我注意到此错误仍适用于Xamarin。

Xamarin错误

解决方案

感谢Xamarin论坛站点上@DirkWilhem的回答，设法解决了此问题。

基本上，将其与其他PackageReference节点一起添加到Xamarin iOS项目的 .csproj 文件中：

 < PackageReference Include = System.Reflection.Emit> 
< Version> 4.3.0< / Version> 
< ExcludeAssets>全部< / ExcludeAssets> 
< / PackageReference> 
  

当然，您需要确保先将nuget软件包添加到iOS软件包中。

Xamarin论坛讨论

I've got a cross platform (iOS and Android) Xamarin solution using .NET Standard 2.0. The solution is being built by Visual Studio 2017 (I've tried both the current and preview versions). The Forms and Android projects build fine. However, the iOS fails to build, with the following error:

1>CSC : error CS1703: Multiple assemblies with equivalent identity have been imported: 'C:\Users\newuser.nuget\packages\system.reflection.emit\4.3.0\ref\netstandard1.1\System.Reflection.Emit.dll' and 'C:\Program Files (x86)\Microsoft Visual Studio\Preview\Enterprise\Common7\IDE\ReferenceAssemblies\Microsoft\Framework\Xamarin.iOS\v1.0\Facades\System.Reflection.Emit.dll'. Remove one of the duplicate references.

I've tried many work arounds as described here:

oren.codes

www.hanselman.com

github.com/NuGet

Unfortunately none of these suggestions work. I have also tried to add the System.Reflection.Emit nuget package directly to the Forms and/or to the iOS projects directly. This doesn't work either. Note that originally, the The System.Reflection.Emit package wasn't referenced directly by anything in the solution. It is being pulled in by the following nuget packages which are being explicitly referenced:

• Acr.DeviceInfo (5.0.5)
• akavache (6.0.0-alpha0038)
• AutoMapper (6.2.2)
• Microsoft.Identity.Client (1.1.1-preview0040)
• Newtonsoft.Json (10.0.3)

Finally, I have tried the update-package -reinstall command in the package console to reinstall all packages for the iOS project. This doesn't work either.

-- update

Just to make this clear, neither the Xamarin Forms or the Xamarin iOS project directly reference System.Reflection.Emit. That package is being pulled in as a dependency of other nuget packages, just from packages that are installed into the Xamarin Forms project. I have confirmed all of the dependencies that are referenced by Nuget, are using the same version. See these screenshots:

It seems to me that the problem (as the error says) is that there is an old version of System.Reflection.Emit that was installed by Visual Studio. However, I can't find a way of ignoring it and using the version of System.Reflection.Emit instead. As I've said above, I have tried to use a project.json file in the Xamarin.iOS project, and manually ignoring, but this doesn't work.

Does anyone else have any ideas?

As an aside, I notice that this bug is still open for Xamarin.

Xamarin Bugs

解决方案

Managed to get this resolved thanks to an answer by @DirkWilhem on Xamarin Forums site.

Basically, add this to your Xamarin iOS project's .csproj file, with the other PackageReference nodes:

<PackageReference Include="System.Reflection.Emit">
  <Version>4.3.0</Version>
  <ExcludeAssets>all</ExcludeAssets>
</PackageReference>

Of course you need to make sure the nuget package has been added to the iOS package first.

Xamarin Forums discussion

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