Sitecore ASP.NET Core Language Switcher Snippets

Default.cshtml

@model LanguageSwitcherModel

@foreach (var culture in Model.SupportedCultures)
{
    if (Model.CurrentUICulture.Name == culture.Name)
    {
        <strong>@culture.DisplayName</strong>
    }
    else
    {
        <a asp-route-culture="@culture.Name" asp-route-sitecoreRoute="@Model.CurrentSitecoreRoute">@culture.DisplayName</a>
    }
}

LanguageSwitcherModel.cs

using System.Collections.Generic;
using System.Globalization;

namespace DevExAcceptance.Models
{
    public class LanguageSwitcherModel
    {
        public CultureInfo CurrentUICulture { get; set; }
        public List<CultureInfo> SupportedCultures { get; set; }
        public string CurrentSitecoreRoute { get; set; }
    }
}

LanguageSwitcherViewComponent.cs

using DevExAcceptance.Models;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Localization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Options;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace DevExAcceptance.ViewComponents
{
    public class LanguageSwitcherViewComponent : ViewComponent
    {
        private readonly IOptions<RequestLocalizationOptions> _localizationOptions;

        public LanguageSwitcherViewComponent(IOptions<RequestLocalizationOptions> localizationOptions)
        {
            _localizationOptions = localizationOptions;
        }

        public async Task<IViewComponentResult> InvokeAsync()
        {
            var cultureFeature = HttpContext.Features.Get<IRequestCultureFeature>();
            var languageSwitcherModel = new LanguageSwitcherModel
            {
                SupportedCultures = _localizationOptions.Value.SupportedCultures.ToList(),
                CurrentUICulture = cultureFeature.RequestCulture.Culture,
                CurrentSitecoreRoute = this.HttpContext.Request.RouteValues["sitecoreRoute"]?.ToString() ?? ""
            };
            return View(languageSwitcherModel);
        }
    }
}

Startup.cs

// Need to configure localization options in ConfigureServices so we can access them later via DI
services.Configure<RequestLocalizationOptions>(options =>
{
    // If you add languages in Sitecore which this site / Rendering Host should support, add them here.
    var supportedCultures = new List<CultureInfo> { new CultureInfo(_defaultLanguage), new CultureInfo("en-GB") };
    options.DefaultRequestCulture = new RequestCulture(_defaultLanguage, _defaultLanguage);
    options.SupportedCultures = supportedCultures;
    options.SupportedUICultures = supportedCultures;

    // Allow culture to be resolved via standard Sitecore URL prefix and query string (sc_lang).
    options.UseSitecoreRequestLocalization();
});

//Then in Configure you can just call
app.UseRequestLocalization();