Startup.cs

using System.Linq;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Versioning;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Swashbuckle.AspNetCore.Swagger;

namespace Jimismith.Versioning.Example
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
                .AddEnvironmentVariables();
            Configuration = builder.Build();
        }

        public IConfigurationRoot Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // Add framework services.
            services.AddMvc();
            // Add API Versioning
            // the default version is 1.0
            // and we're going to read the version number from the media type
            // incoming requests should have a accept header like this: Accept: application/json;v=1.0
            services.AddApiVersioning(o =>
            {
                o.DefaultApiVersion = new ApiVersion(1, 0);
                o.AssumeDefaultVersionWhenUnspecified = true;
                o.ApiVersionReader = new MediaTypeApiVersionReader();
            });
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1.1", new Info { Title = "Versioned Api v1.1", Version = "v1.1" });
                c.SwaggerDoc("v1.0", new Info { Title = "Versioned Api v1.0", Description = "Deprecated", Version = "v1.0" });
                c.DocInclusionPredicate((docName, apiDesc) =>
                {
                    var actionApiVersionModel = apiDesc.ActionDescriptor?.GetApiVersion();
                    // would mean this action is unversioned and should be included everywhere
                    if (actionApiVersionModel == null)
                    {
                        return true;
                    }
                    if (actionApiVersionModel.DeclaredApiVersions.Any())
                    {
                        return actionApiVersionModel.DeclaredApiVersions.Any(v => $"v{v.ToString()}" == docName);
                    }
                    return actionApiVersionModel.ImplementedApiVersions.Any(v => $"v{v.ToString()}" == docName);
                });
                c.OperationFilter<ApiVersionOperationFilter>();
            });
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            app.UseMvc();
            app.UseSwagger();
            app.UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint("/swagger/v1.1/swagger.json", "Versioned Api v1.1");
                c.SwaggerEndpoint("/swagger/v1.0/swagger.json", "Versioned Api v1.0");
            });
        }
    }
}