Best way to build a JSON API coupled with HTML views in a Rails project

I’ve got a Rails eCommerce project communicating with an iOS app. The iOS app receives JSON data from the Rails back-end, but there’s also HTML rendering when a user comes to the project from his browser. They basically call the same actions (create, destroy, update, etc.) from both sides.

/website/my_action → HTML rendering
/website/my_action.json → API

What’s the best way to organize our Rails app to stay DRY and avoid messy code / code smell ? The project currently uses respond_to a lot but i’m wondering if we shouldn’t switch to a split system with default json response:

/api/v1/my_action
/website/my_action

And if so, how would you do concretely?

Here’s a sample of one method in the current system

  def get_following

    @user = User.find(params[:id]) 

    respond_to do |format|
      format.html { render :index }
      format.json { render :json => ApiFormat.success(:followers, user.following) }
    end

  end

It looks fine but becomes very messy in some methods I prefer not to show. In short: how would you refacto the project in a more efficient way?