1)Export Facebook Calendar:
-Go to events.
-At the end of the page click on "Export birthdays" and copy the URL.
2)Import to Gmail:
-Go to Google Calendar, Other calendar/Add by URL, and paste the URL from facebook.
3)Share calendar to iPhone
-Follow this steps from Google to sync your calendar.
-Go to Calendar settings/Calendars.
-Enable "Contacts, Birthdays and Events".
-By default, only the default calendar is synced to your iPhone. Go here to enable additional calendars: https://www.google.com/calendar/iphoneselect
I hope it will be useful.
bye
