ASP.Net MVC 4 Web API controller doesn't work with Unity.WebApi

The handling of Controller and ApiController is different as they have completely different base classes:

I use Unity.MVC4 library for controller DI (http://www.nuget.org/packages/Unity.MVC4/)

Install-Package Unity.MVC4

and Unity.WebAPI for DI (http://www.nuget.org/packages/Unity.WebAPI/)

Install-Package Unity.WebAPI

Your bootstrapper should be a combination of both:

DependencyResolver.SetResolver(new Unity.Mvc4.UnityDependencyResolver(container));
GlobalConfiguration.Configuration.DependencyResolver = new Unity.WebApi.UnityDependencyResolver(container);

Note I also had to do to add some registration to get the Help page to work

container.RegisterInstance(typeof (HttpConfiguration), GlobalConfiguration.Configuration);

As the owner of Unity.MVC4 I am looking at getting WebApi implemented within our library.