Set a cookie to persist the Facebook canvas session (works with Safari)

facebook_cookie.rb

# Put this in application_controller.rb
# See http://blog.coderubik.com/2011/03/cookies-and-facebook-canvas-apps for details

before_filter :set_facebook_cookie

def set_facebook_cookie
  response.headers['P3P'] = 'CP="IDC DSP COR ADM DEVi TAIi PSA PSD IVAi IVDi CONi HIS OUR IND CNT"'
  if params[:signed_request]
    cookies["sr_#{Facebooker2.app_id}"] = params[:signed_request]
  else
    params[:signed_request] = cookies["sr_#{Facebooker2.app_id}"]
  end
end