Platform Preferences

The Platform Preferences provider wraps the native platform preferences (Android SharedPreferences, iOS NSUserDefaults) as an IConfiguration source. Unlike most providers, this one supports write-back - you can set values via IConfiguration and they will be persisted across app restarts.

Setup

var config = new ConfigurationBuilder()
    .AddPlatformPreferences()
    .Build();

Write-Back Support

You can write values directly through IConfiguration:

IConfiguration config = ...; // build
config["key"] = "value"; // persists to platform preferences

Writing a value will:

1. Persist the value to the platform’s native preferences store
2. Trigger change notifications via IOptionsMonitor<T>

Change Notifications

When combined with IOptionsMonitor<T>, you get reactive updates whenever a preference value changes:

services.Configure<MySettings>(config.GetSection("MySettings"));

// In your service/viewmodel
public class MyService
{
    public MyService(IOptionsMonitor<MySettings> options)
    {
        options.OnChange(settings =>
        {
            // React to configuration changes
        });
    }
}

Platform Implementations

Platform	Backing Store
Android	SharedPreferences
iOS / Mac Catalyst	NSUserDefaults