使用Graph API发布到Facebook群组

Need some help understanding the Facebook documentation.

Using the Facebook Graph API, Can you log users into your site then allow them to post to a Facebook group?

Or is it only the group admin that can post to the group. If so, does anyone know if this is something that has changed recently ?

https://developers.facebook.com/docs/graph-api/reference/v2.5/group/feed

Can you log users into your site then allow them to post to a Facebook group?

A specific Facebook group yes. As long as you know the ID beforehand.

For everything else the only groups available will be those seen from user_managed_groups