TodoController.cs

public void Configure(IAppBuilder appBuilder)
{
    this.container.RegisterSingle<ITodoRepository>(() => new TodoDatabase(this.slowness, this.todoCount));
    var httpConfig = new HttpConfiguration();
    httpConfig.Routes.MapHttpRoute(
        "DefaultApi",
        "{controller}/{id}",
        new { id = RouteParameter.Optional });

    httpConfig.DependencyResolver = new SimpleInjectorDependencyResolver(this.container);
    appBuilder.UseWebApi(httpConfig);
}


public class TodoController : ApiController
{
    private readonly ITodoRepository repository;
    public TodoController(ITodoRepository repository)
    {
        Ensure.ArgumentNotNull(repository, "repository");
        this.repository = repository;
    }
        public async Task DeleteAsync(int id)
    {
        await this.repository.RemoveAsync(id);
    }
        public async Task<Todo> GetAsync(int id)
    {
        return await this.repository.GetByIdAsync(id);
    }
    public async Task<IEnumerable<Todo>> GetAsync()
    {
        return await this.repository.GetAllAsync();
    }
    public async Task PutAsync(Todo todo)
    {
        await this.repository.AddAsync(todo);
    }
}