How-To: Get Started with Hosting

Hosting can be used to register services that will be accessible throughout the application via dependency injection (DI). This tutorial will walk you through the critical steps needed to leverage hosting in your application.

Important

This guide assumes you used the template wizard or dotnet new unoapp to create your solution. If not, it is recommended that you follow the Creating an application with Uno.Extensions documentation to create an application from the template.

Step-by-step

1. Installation

Add Hosting to the <UnoFeatures> property in the Class Library (.csproj) file. If you already have Extensions in <UnoFeatures>, then Hosting is already installed, as its dependencies are included with the Extensions feature.
```
<UnoFeatures>
    Material;
+   Hosting;
    Toolkit;
    MVUX;
</UnoFeatures>
```

2. Create and Configure IApplicationBuilder

We need to expose the IHost instance to the rest of App.cs. Add the following property to your class file:
```
private IHost Host { get; set; }
```
The IHost type is defined in the Microsoft.Extensions.Hosting namespace. Since this and other related types will be used throughout this guide, it's recommended to add this namespace to your GlobalUsings.cs file for convenience and cleaner code.
```
global using Microsoft.Extensions.Hosting;
```

As soon as your app is launched, use the CreateBuilder() extension method to instantiate an IApplicationBuilder from your Application object:

protected override void OnLaunched(LaunchActivatedEventArgs e)
{
    var appBuilder = this.CreateBuilder(args)
    .Configure(host => {
        // Configure the host builder
    });
    ...
}

3. Set Up the Main Window with the Builder

Replace MainWindow = new Window() or any MainWindow assignment with the builder approach:

protected override void OnLaunched(LaunchActivatedEventArgs e)
{
    var appBuilder = this.CreateBuilder(args)
    .Configure(host => {
        // Configure the host builder
    });

    MainWindow = builder.Window;
    ...
}

4. Build the IHost

Finally, build the host and assign it to the Host property:

protected override void OnLaunched(LaunchActivatedEventArgs e)
{
    var appBuilder = this.CreateBuilder(args)
    .Configure(host => {
        // Configure the host builder
    });

    MainWindow = builder.Window;

    Host = appBuilder.Build();
    ...
}