I have done that using:
this let you share your score by publishing in someone profile.
with the browser plugin you create a browser go to action an there you call a facebook dialog with your information :
"https://www.facebook.com/dialog/feed?
app_id=XXX
&display=popup&caption= XXX
&link=https%3A%2F%2Fdevelopers.facebook.com%2Fdocs%2Fdialogs%2F
&redirect_uri=https://facebook.com
&name=XXX
&picture=XXXX.png
&description= XXX"
it works me on android, but i dont know why it dosent work on iOS, and Windows phone, like in this forum said
XXX is replaced by name of profile facebook for example ?
and for twitter ? its same ?