Facebook API - How could I count invited friends by user of my app?

Question

I know that it is possible, I saw it few months ago in one app. I would like to achieve condition: if user invited 3 or more friends then... - How I could check it?

How could I show how many users are checked to invite? (I would use multi-friend-selector )

Answer 1

The invited friends come into an array which can be accessed like this:

if(isset($_POST["ids"]))
{
   $count_invites = count($_POST["ids"]);

   // insert $count_invites into database against current user

}