How to add my custom .NET MAUI class library output dlls to .NET MAUI app?

Question

How to add my custom .NET MAUI class library output dlls to .NET MAUI app?

Tamer Irdais 26

I have created a .NET MAUI class library single project that when built it generates multiple dlls each one inside platform specific folder.
Now I am having difficulties figuring out how to reference this class library dlls inside my .NET MAUI app, when I add them all even if I use Conditions I keep getting error below which is AppHostBuilderExtensions extension method inside my library:
The call is ambiguous between the following methods or properties: 'MyLibrary.Hosting.AppHostBuilderExtensions.ConfigureLibrary'

So what's the best way to reference class library multiple dlls inside MAUI app?

<Reference Include="MyLibrary">  
    <SpecificVersion>False</SpecificVersion>  
    <HintPath>MyLibraryOutputPath/MyLibrary.dll</HintPath>  
    <Private>False</Private>  
</Reference>  
<Reference Include="MyLibrary.Android" Condition="$(TargetFramework.StartsWith('net6.0-android'))">  
    <SpecificVersion>False</SpecificVersion>  
    <HintPath>MyLibraryOutputPath/net6.0-android/MyLibrary.Android.dll</HintPath>  
    <Private>False</Private>  
</Reference>

The problem turned out to be with the <Private>False</Private> element, when I removed it from the app references the app compiles and runs fine but I have below 2 issues now:

1- If I changed my library output DLLs names so that each platform has different name like "<LibName>.<PlatformName>.dll" I get below compilation error when using the library from inside XAML files:

MainPage.xaml : XamlC error : Failed to resolve assembly: 'MauiLib1, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'

My library DLLs names are as below and we need then to have different names because when we distribute them we put then in one folder among other DLLs of our toolkit:
net6.0: MyLibrary.dll
net6.0-android: MyLibrary.Android.dll
net6.0-ios: MyLibrary.iOS.dll
net6.0-windows: MyLibrary.Windows.dll

Any idea how to achieve this?

2- Even if I kept the library output DLLs names identical (without adding platform names) for each platform it compiles and runs BUT when you open the XAML file it shows warning underlines under the types I use from inside my library, any idea why? I even tried to close VS and cleaned my MAUI app generated folders/files but still the types I use from inside the library are highlighted as warnings and I get no intelli-sense for them.

I don't know if I can attach projects here but I couldn't find any option to do that so I uploaded my project to github and below is the link to it for your reference so you can check the above issues on your side:

https://github.com/TamerIrdais/.NET-MAUI-App-With-References-to-MAUI-Class-Library

I am using Microsoft Visual Studio Enterprise 2022 Version 17.3.0 Preview 5.0 but I don't know how to get the MAUI version.

Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2022-07-27T09:04:59.033+00:00

Hi @Tamer Irdais , From the code snippets you provided, I saw you added the shared dll and the Android dll. May I ask your VS version and your MAUI version? And would you mind sharing the detailed error message? In addition, how did you create the .NET MAUI class library project? What did you try? As noted in the Q&A FAQ: How to write a quality question
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2022-08-01T09:40:14.28+00:00

Hi @Tamer Irdais , I removed your answer and added the information to the question.

Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Microsoft External Staff

You could try to remove the dll reference from the MAUI project :

<!--<Reference Include="MyLibrary"> // Remove dll reference In `MAUIApp1.csproj`  
     <SpecificVersion>False</SpecificVersion>  
     ...  
 </Reference>-->

And remove AssemblyName and TargetName in your MAUI Class Library

<!--<AssemblyName>MauiLib1</AssemblyName>  
      <RootNamespace>MauiLib1</RootNamespace>-->//remove in `MauiLib1.csproj`:  

 <!--<PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Debug|net6.0|AnyCPU'">  
      <DefineConstants>$(DefineConstants)TRACE</DefineConstants>  
      <TargetName>MauiLib1</TargetName>  
   </PropertyGroup> ......  
      <TargetName>MauiLib1.Windows</TargetName>  
   </PropertyGroup>-->// remove

Then try to right-click your MAUI project and set it as the setup project, go to Add->Project Reference-> Solution, check your MauiLib1. The reference will be added to your MAUIApp1.csproj :

 <ItemGroup>  
     <ProjectReference Include="..\MauiLib1\MauiLib1.csproj" />  
   </ItemGroup>

After that, you can run and check if this issue still exists. If you still want to add the dll reference, please try to create a nuget package, and set dlls as the local nuget package source, then add the local nuget package source to your MAUI project.

Tamer Irdais 26 Reputation points

2022-08-02T14:39:17.317+00:00

Thank you @Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) but none of your suggestions work for me, I can't add my library as project reference not as a nuget right now because I need to be able to debug it, I need to add the dlls as references just like we used to do with Xamarin.Forms, but its not working if the platforms dlls have different names and if they do it works but the VS studio doesn't provide intelli-sense for my control and also couldn't resolve it although it builds and runs fine in this case.

If this is a bug that needs to be fixed then we should report it right?

Meanwhile do you have any other suggestions to make it work with DLLs references?
Tamer Irdais 26 Reputation points

2022-08-17T05:30:02.633+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) Shouldn't this work with DLLs references like the Xamarin used to work?

1 answer

Your answer

Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2022-07-27T09:04:59.033+00:00

Hi @Tamer Irdais , From the code snippets you provided, I saw you added the shared dll and the Android dll. May I ask your VS version and your MAUI version? And would you mind sharing the detailed error message? In addition, how did you create the .NET MAUI class library project? What did you try? As noted in the Q&A FAQ: How to write a quality question
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2022-08-01T09:40:14.28+00:00

Hi @Tamer Irdais , I removed your answer and added the information to the question.
Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) 36,436 Reputation points Microsoft External Staff

2022-08-01T09:56:51.607+00:00

You could try to remove the dll reference from the MAUI project :



And remove AssemblyName and TargetName in your MAUI Class Library

//remove in `MauiLib1.csproj`: // remove

Then try to right-click your MAUI project and set it as the setup project, go to Add->Project Reference-> Solution, check your MauiLib1. The reference will be added to your MAUIApp1.csproj :

<ItemGroup> <ProjectReference Include="..\MauiLib1\MauiLib1.csproj" /> </ItemGroup>

After that, you can run and check if this issue still exists. If you still want to add the dll reference, please try to create a nuget package, and set dlls as the local nuget package source, then add the local nuget package source to your MAUI project.
Tamer Irdais 26 Reputation points

2022-08-02T14:39:17.317+00:00

Thank you @Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) but none of your suggestions work for me, I can't add my library as project reference not as a nuget right now because I need to be able to debug it, I need to add the dlls as references just like we used to do with Xamarin.Forms, but its not working if the platforms dlls have different names and if they do it works but the VS studio doesn't provide intelli-sense for my control and also couldn't resolve it although it builds and runs fine in this case.

If this is a bug that needs to be fixed then we should report it right?

Meanwhile do you have any other suggestions to make it work with DLLs references?
Tamer Irdais 26 Reputation points

2022-08-17T05:30:02.633+00:00

@Wenyan Zhang (Shanghai Wicresoft Co,.Ltd.) Shouldn't this work with DLLs references like the Xamarin used to work?

Answer 1

Lukas Kuchta 1

Did you try make your PCL as nuget and add whole nuget instead of dll one by one ? It should be worked. Like MauiCommunityToolkit it PCL and whe you check the strcture of packe it is simila inside lib folder like output from pcl in bin.

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How to add my custom .NET MAUI class library output dlls to .NET MAUI app?

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