Migrating Projects to Single Project

The Uno Platform 5.2 and later use the Uno.Sdk which provides a single Uno Project structure and a single location for updating the Uno Platform core packages version in global.json.

[!IMPORTANT] Migrating to the Uno.Sdk and Single Project are not required. Existing projects, 5.1 and earlier, continue to be supported in Uno Platform 5.2 or later.

With Uno Platform Single Project, you can optimize your project structure and simplify maintenance while leveraging the power of Uno Platform for cross-platform app development. This guide provides step-by-step instructions and practical tips to ensure a smooth migration process. Let's get started!

What is the Uno.Sdk

The Uno.Sdk is used to abstract the complexity needed to build cross-platform projects, while still ensuring that you have the ability to customize the configuration to your needs.

This means that values such as the SupportedOSPlatformVersion, which have been in the template's Directory.Build.props in previous Uno Platform templates, now have a default value set to the minimum supported by Uno Platform.

If you need to be more restrictive for your specific project you can provide your overrides for the platform(s) that you need.

Project Structure

In the Uno Platform Single Project, all platform-specific code is put together in one project. Instead of having separate projects for each platform, everything is organized within a Platforms folder. This folder contains sub-folders for each platform your project targets, like Android, iOS, Skia, WebAssembly, and Windows. Each platform folder stores the code and resources needed for that platform, making development easier to manage for multi-platform projects.

Upgrading an existing project to Single Project

The following sections detail how to upgrade an existing project to use a single project with the Uno.Sdk. Those modifications are made in place and it is strongly recommended to work on a source-controlled environment.

While following this guide, you can compare with a new empty project created using our Wizard, or using dotnet new templates.

Migrating to a Single Project

Migrating from a 5.1 or earlier template is a matter of merging all the csproj files for all the platforms heads down to one csproj file.

We'll take the example of an Uno Platform 5.0 blank app, called MyApp, to migrate to Single Project :

In a separate folder from your existing app, create a new app using the same name as your app:
bash
```
dotnet new unoapp -o MyApp --preset=recommended
```
This will allow for taking pieces of the structure with the proper namespaces. If your app was created using the blank template, use --preset=blank instead. You can also use the Live Wizard or the Visual Studio Wizard and select the same optional features you used for your app.

Next to the solution, create a global.json file

json

{
    "msbuild-sdks": {
        "Uno.Sdk": "{Current Version of Uno.WinUI/Uno.Sdk}"
    }
}

From the empty app created at step one:
- Take the contents of the MyApp.csproj and copy it over your own MyApp.csproj
- Take the folder named Properties and copy it over your own MyApp
If you have your own PackageReference and ProjectReference, make sure to preserve them.
From the empty app created at step one, take the Platforms folder and copy it over your own MyApp folder.

In you app's MyApp.csproj, create the following block:

xml

<Choose>
  <When Condition="'$(TargetFramework)'=='net10.0-ios'">
  </When>
  <When Condition="'$(TargetFramework)'=='net10.0-android'">
  </When>
  <When Condition="'$(TargetFramework)'=='net10.0-windows10.0.19041'">
  </When>
  <When Condition="'$(TargetFramework)'=='net10.0-desktop'">
  </When>
  <When Condition="'$(TargetFramework)'=='net10.0-browserwasm'">
  </When>
</Choose>

This will allow us to place custom project configurations in each of those sections. Use the ones that are relevant to your project targets.

From the empty app created at step one, take the App.xaml and App.xaml.cs and copy those over your own MyApp folder.
Copy the individual modifications you made to your AppResources.xaml and App.cs into App.xaml and App.xaml.cs, respectively. Those can, for instance, be changes made to OnLaunched, InitializeLogging, or RegisterRoutes.
For the WebAssembly project, most of the configuration is now included by the Uno.Sdk. You can:
1. Move all the files from your MyApp.Wasm folder to the Platforms/WebAssembly folder, except MyApp.Wasm.csproj and the Properties folder.
2. Copy the individual configurations, ProjectReference and PackageReference entries from your MyApp.Wasm.csproj to your MyApp.csproj, into the appropriate When condition block we created above. This can include properties like WasmShellGenerateAOTProfile or WasmShellMonoRuntimeExecutionMode, depending on your choices.
3. Delete the MyApp.Wasm folder
For the Mobile project, you can:
1. In your app, move the folders MyApp.Mobile/Android, MyApp.Mobile/iOS to the MyApp/Platforms.
2. Copy the individual configurations, ProjectReference and PackageReference entries from your MyApp.Mobile.csproj to your MyApp.csproj, into the appropriate When condition block we created above. This can include properties like ApplicationTitle or ApplicationId, depending on your choices.
3. Delete the MyApp.Mobile folder
For the Skia.Gtk, Skia.Wpf and Skia.Framebuffer projects, you can:
1. Copy individual modifications made to the Program.cs of each platform over to Platforms/Desktop/Program.cs
2. Copy the individual configurations, ProjectReference and PackageReference entries from your MyApp.Skia.[Gtk|Wpf|Framebuffer].csproj to your MyApp.csproj, into the appropriate When condition block we created above.
3. You can also copy the individual modifications made to app.manifest and Package.manifest to MyApp. Those two files are now shared across platforms.
4. Delete the MyApp.Skia.[Gtk|Wpf|Framebuffer] folders
For the MyApp.Windows project, you can:
1. Copy the individual configurations, ProjectReference and PackageReference entries from your MyApp.Windows.csproj to your MyApp.csproj, into the appropriate When condition block we created above.
2. You can copy the individual modifications made to app.manifest and Package.manifest to MyApp. Those two files are now shared across platforms.
For the MyApp.[Shared|Base] project, you can:
1. Move the Icons and Splash folders to the MyApp/Assets
2. If you've made modifications to the base.props file, you can copy those over to the MyApp.csproj, outside the Choose section.
3. If you've made individual changes to the AppHead.xaml file, copy those over to the App.xaml file
4. If you've made individual changes to the AppHead.xaml.cs file, copy those over to the App.xaml.cs file
5. Delete the MyApp.[Shared|Base] folder
In All the .cs files, replace AppHead with App
Once done, you can remove the Platforms folder from your solution explorer, as all other platform heads have been deleted.

If you have a MyApp.Server project, make sure to change from:

xml

<ProjectReference Include="..\MyApp.Wasm\MyApp.Wasm.csproj" />

xml

<ProjectReference 
    Include="..\MyApp\MyApp.csproj"
    SetTargetFramework="TargetFramework=net10.0-browserwasm"
    ReferenceOutputAssembly="false" />

From the empty app created at step one, take the Directory.Build.props and Directory.Build.targets files and copy those over your own root folder. Make sure to copy individual changes made in your file, such as CSharpVersion or Nullable.
From the empty app created at step one, take the Directory.Packages.propsfile and copy it over to your own root folder. All of the NuGet packages can be removed from this file, as the Uno.SDK provides those automatically.
In all the projects files, replace $(DotnetVersion) with net10.0
Remove the solution-config.props.sample file. This part is now handled by Uno Platform automatically.

At this point, your solution can be compiled using a single project and Uno Platform 5.2. For a guide through using the new single project, head over to our getting started.

Wrapping up

Now that your project has gotten simplified, you can head over to our Uno.Sdk documentation to explore its features.