调用未定义的方法Illuminate \ Routing \ Route :: header（）

In Laravel 4. I am trying to set the specific header to my route.

I have

Route::filter('api', function($response){
    $response->header("Access-Control-Allow-Origin","*");
    if (Input::get('key') != 'bheng')
    {
        return Response::view('errors.404', array(), 404);
    }
});

I kept getting

Call to undefined method Illuminate\Routing\Route::header()

I'm trying to set it, so I don't get the CORS error anymore.

Any hint on that will be greatly appreciated !!!

Based on Laravel documentation

After filters receive a $response as the third argument passed to the filter

  Route::filter('log', function($route, $request, $response)

   {
        //
   })