在Sqlite.net PCL中找不到SQLitePlatformIOS

Question

I've used nuget package manager to download this package

The example shows:

public class SQLiteFactoryiOS : ISQLiteFactory
{
    public SQLite.Net.SQLiteConnection CreateConnection(string dbName)
    {
        var path = System.IO.Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), dbName);
        return new SQLite.Net.SQLiteConnection(new SQLitePlatformIOS(), path);
    }
}

The issue I am facing is that I can't reference SQLitePlatformIOS. I even found it in the source code , but I'm not able to reach the .Platform namespace, thus I'm unable to create a SQLitePlatformIOS object.

 using SQLite.Net; //.Platform.XamarinIOS <-- Compiler error if I try to reach this

The project I'm using to reference this is a portable class project, because in the references folder I see .NET Portable Subset.

The structure of the project is

iOS MainProject references Example Portable Project Example Portable Project references SQLite.Net-PCL

In the Portable Project I have

References
     .NET Portable Subset
     From Packages
          SQLite.Net
Packages
     SQLite.Net-PCL
Data
     Repositories
           ExampleRepository.cs

My example repository is

using System;
using Example.Data.DTO;
using Example.Models.Properties;

using SQLite.Net;

namespace Example.Data.Repositories
{
    public class ExampleRepository(string dbPath)
    {
        using (var db = new SQLite.Net.SQLiteConnection(new SQLitePlatformIOS() /* Can't reference */, dbPath))
        {
             db.CreateTable<ExampleDTO>();
        }
    }
}

And I call this class from the iOS project.

partial void SaveObject(NSObject sender)
{
    var objectToSave = CreateObjectFromView();
    var dbPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), "Test.db3");
    var repo = new ExampleRepository(dbPath);
}

Answer 1

The reason you're not finding the reference to the iOS implementation is because you don't have access to platform specific code in a PCL. In fact, you don't need it. All you need inside the PCL is the interface, the specific code will be injected using a DI framework, so the PCL uses the proper code for each platform without you having to check which platform you're using during runtime.

Here you can see an example on how dependency injection works (and it even uses SQLite)

Answer 2

Yes, the .Platform namespace has disappeared from the SQLite.Net PCL package.

The workaround is to download the source from https://github.com/oysteinkrog/SQLite.Net-PCL and then build the binaries yourself. To do this, open the solution in Xamarin Studio (as of typing this I'm on 5.10.3 Build 51), change the mode to Release (without targeting any specific hardware), and click Build -> Build All .

Then open your iOS project in Xamarin Studio, right-click on the References folder and select Edit References... , then click on the .Net Assembly tab, click Browse... and browse to the location of the SQLite.Net.Platform.XamarinIOS.Unified.dll file which you've just built. It should be in SQLite.Net-PCL-master/SQLite.Net.Platform.XamarinIOS.Unified/bin/Release

Although an old post from 2014, I found the SQLite.Net PCL GitHub link from https://forums.xamarin.com/discussion/28916/error-while-trying-to-install-sqlite-net-platform-xamarinios-2-4-1-please-help (See JuhaPehkonen's Dec 2014 post)

And a bit more info on adding references in Xamarin Studio can be found here: How to add libraries to Xamarin References lists