MAUI应用iOS平台操作SQLite时触发System.Windows.Forms加载失败异常

问题场景 #

MAUI应用读写本地SQLite数据库时，Android平台运行正常，iOS平台抛出文件找不到异常。

异常详情 #

System.IO.FileNotFoundException: 无法加载文件或程序集'System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'或其依赖项之一。
文件名: 'System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'
at MyApp.SqlHelper.GetConnection() in /Users/MyCompany/Projects/MyProject-maui/MyProject/Renderers/SqlHelper.cs:line 28
at MyApp.SqlHelper..ctor() in /Users/MyCompany/Projects/MyProject-maui/MyProject/Renderers/SqlHelper.cs:line 18
at MyProject.App.get_Database() in /Users/MyCompany/Projects/MyProject-maui/MyProject/App.xaml.cs:line 92

已安装的NuGet包 #

<PackageReference Include="sqlite-net-pcl" Version="1.8.116" />
<PackageReference Include="SQLiteNetExtensions.Async" Version="2.1.0" />
<PackageReference Include="SQLitePCLRaw.core" Version="2.1.6" />
<PackageReference Include="SQLitePCLRaw.bundle_green" Version="2.1.6" />
<PackageReference Include="SQLitePCLRaw.provider.dynamic_cdecl" Version="2.1.6" />
<PackageReference Include="SQLitePCLRaw.provider.sqlite3" Version="2.1.6" />

相关代码片段 #

App.xaml.cs #

public static SqlHelper Database
{
    get
    {
        if (database == null)
        {
            database = new SqlHelper();
        }
        return database;
    }
}

SqlHelper.cs #

public SqlHelper()
{
    database = GetConnection();//异常触发于此行
    database.CreateTable<Favorites>();
}

GetConnection方法 #

public SQLite.SQLiteConnection GetConnection()
{
    SQLiteConnection sqlitConnection;
    var sqliteFilename = "Favorites.db3";
    IFolder folder = FileSystem.Current.LocalStorage;
    string path = PortablePath.Combine(folder.Path.ToString(), sqliteFilename);
    sqlitConnection = new SQLite.SQLiteConnection(path);
    return sqlitConnection;
}

解决步骤 #

1. 精简NuGet依赖
   SQLitePCLRaw.bundle_green已包含SQLitePCLRaw.core、基础提供者等核心组件，移除重复安装的SQLitePCLRaw.core、SQLitePCLRaw.provider.dynamic_cdecl、SQLitePCLRaw.provider.sqlite3包，避免跨平台依赖冲突。

2. 修正路径处理逻辑
   iOS平台对文件路径有特殊要求，替换PortablePath.Combine为MAUI原生的Path.Combine，并使用AppDataDirectory确保路径正确性：

   public SQLite.SQLiteConnection GetConnection()
   {
       var sqliteFilename = "Favorites.db3";
       string path = Path.Combine(FileSystem.Current.AppDataDirectory, sqliteFilename);
       return new SQLite.SQLiteConnection(path);
   }
   

3. 验证iOS平台原生库配置
   确认iOS项目自动引入对应平台的SQLite原生库（SQLitePCLRaw.bundle_green通常会自动处理），若仍有问题，可单独添加SQLitePCLRaw.provider.sqlite3.ios包。

4. 清理重建项目

   • 删除所有项目的bin和obj目录
   • 卸载并重新安装所有NuGet包
   • 重启开发工具后重新编译iOS项目

内容的提问来源于stack exchange，提问作者Sreejith Sree