title: how to get posts from facebook page using GraphAPI in swift
body: <p>My app had a functionality which is : get posts from Facebook page and show it in the app. 
  i searched and i found that i should use Facebook GraphAPI : 
  <a href="https://developers.facebook.com/docs/graph-api/using-graph-api/v2.3#reading" rel="nofollow noreferrer">https://developers.facebook.com/docs/graph-api/using-graph-api/v2.3#reading</a>
  i follow the previous link, but i get error : 
  <strong>"An access token is required to request this resource."</strong>
  i have the access token for the page, but i really don't know how to assign it in my request. 
  any help please?
  thanks a lot!</p>