.NET MAUI iOS下Entity Framework Core的裁剪与链接器配置问题

问题背景 #

将使用Entity Framework Core 3.1 + SQLite的Xamarin Forms 5.0应用迁移至.NET MAUI 6.0 + EF Core 6.0后，Debug构建正常，但iOS的Release构建启动即崩溃，Android Release构建无异常。

复现步骤 #

1. 在Visual Studio中创建.NET MAUI App模板项目，编辑项目文件添加以下配置以支持dotnet build：

<PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Debug|net6.0-ios|AnyCPU'">
  <CreatePackage>false</CreatePackage>
  <CodesignProvision>Automatic</CodesignProvision>
  <CodesignKey>iPhone Developer</CodesignKey>
  <RuntimeIdentifier>ios-arm64</RuntimeIdentifier>
</PropertyGroup>
<PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Release|net6.0-ios|AnyCPU'">
  <CreatePackage>false</CreatePackage>
  <CodesignProvision>Automatic</CodesignProvision>
  <CodesignKey>iPhone Distribution</CodesignKey>
  <RuntimeIdentifier>ios-arm64</RuntimeIdentifier>
</PropertyGroup>

2. 终端执行以下命令运行Release构建（替换项目名和设备UDID）：

dotnet build MauiEFCore.csproj -c Release -f net6.0-ios -t:Run -p:_DeviceName=<Device UDID>

此时应用可正常运行；但添加EF Core相关包后启动崩溃：

<ItemGroup>
  <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="6.0.11" />
  <PackageReference Include="SQLitePCLRaw.bundle_e_sqlite3" Version="2.1.3" />
</ItemGroup>

错误现象 #

启动后控制台输出包含AOT加载错误，随后触发SIGABRT崩溃：

Launched application 'com.companyname.mauiefcore' on 'Gerwin's iPhone 11' with pid 25752
2023-01-06 16:00:53.767 MauiEFCore[25752:10999573] error: Failed to load AOT module 'Microsoft.Maui.Graphics' while running in aot-only mode because a dependency cannot be found or it is out of date.

=================================================================
    Native Crash Reporting
=================================================================
Got a SIGABRT while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your application.
=================================================================

// 省略冗长的Native栈追踪...

Application 'com.companyname.mauiefcore' terminated (with exit code '' and/or crashing signal '6).

已尝试的无效操作 #

• 添加<MtouchLink>None</MtouchLink>禁用链接，但构建仍显示正在进行程序集大小优化（裁剪），崩溃未解决
• 尝试关闭裁剪（设置<PublishTrimmed>false</PublishTrimmed>），但触发错误：iOS projects must build with PublishTrimmed=true
• 在Xamarin Forms中曾使用的--linkskip System.Core参数在MAUI中被忽略，构建日志显示Skipping unknown argument 'linkskip'
• 添加EF Core相关程序集（Microsoft.EntityFrameworkCore.Abstractions、SQLitePCLRaw.provider.internal）的链接保留设置，无效

解决方案建议 #

针对.NET MAUI iOS的裁剪/AOT特性，需通过以下配置确保EF Core相关组件不被错误裁剪：

1. 添加链接器描述文件 #

在项目中创建linker.xml文件，内容如下：

<linker>
  <assembly fullname="Microsoft.EntityFrameworkCore">
    <type fullname="*" />
  </assembly>
  <assembly fullname="Microsoft.EntityFrameworkCore.Sqlite">
    <type fullname="*" />
  </assembly>
  <assembly fullname="SQLitePCLRaw.core">
    <type fullname="*" />
  </assembly>
  <assembly fullname="SQLitePCLRaw.provider.sqlite3">
    <type fullname="*" />
  </assembly>
  <assembly fullname="Microsoft.EntityFrameworkCore.Abstractions">
    <type fullname="*" />
  </assembly>
</linker>

并在项目文件中引用该文件：

<ItemGroup>
  <LinkerDescriptor Include="linker.xml" Condition="'$(TargetFramework)' == 'net6.0-ios'" />
</ItemGroup>

2. 调整AOT和裁剪参数 #

在Release的iOS属性组中添加以下配置，确保EF Core的动态特性被兼容：

<PropertyGroup Condition="'$(Configuration)|$(TargetFramework)|$(Platform)'=='Release|net6.0-ios|AnyCPU'">
  <!-- 保留原有配置 -->
  <CreatePackage>false</CreatePackage>
  <CodesignProvision>Automatic</CodesignProvision>
  <CodesignKey>iPhone Distribution</CodesignKey>
  <RuntimeIdentifier>ios-arm64</RuntimeIdentifier>
  <!-- 添加以下配置 -->
  <PublishTrimmed>true</PublishTrimmed>
  <TrimMode>partial</TrimMode>
  <AotAssemblies>true</AotAssemblies>
  <EnableLLVM>true</EnableLLVM>
  <!-- 排除EF相关程序集的裁剪 -->
  <TrimmerRootAssembly Include="Microsoft.EntityFrameworkCore" />
  <TrimmerRootAssembly Include="Microsoft.EntityFrameworkCore.Sqlite" />
  <TrimmerRootAssembly Include="SQLitePCLRaw.bundle_e_sqlite3" />
</PropertyGroup>

3. 更新依赖包版本 #

尝试将EF Core和SQLitePCLRaw包更新至.NET 6的最新稳定版本，确保与MAUI的兼容性：

<ItemGroup>
  <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="6.0.25" />
  <PackageReference Include="SQLitePCLRaw.bundle_e_sqlite3" Version="2.1.6" />
</ItemGroup>

4. 验证SQLite原生库集成 #

确保SQLitePCLRaw的原生库被正确嵌入，可添加以下配置强制嵌入：

<ItemGroup Condition="'$(TargetFramework)' == 'net6.0-ios'">
  <NativeReference Include="$(NuGetPackageRoot)sqlitepclraw.lib.e_sqlite3/2.1.6/runtimes/ios-arm64/native/libe_sqlite3.a" />
</ItemGroup>

内容的提问来源于stack exchange，提问作者Glorfindel