Get the item amount from inventory

Hi!
I need help, how to heck if player has get ex. 30 diamonds on inventory (not in hand) and send message like: "you got a 30 diamonds"?

PHP:

Foreach ( $inventory->getContents()  as  $inv ):
if($inv->getId() == 264 && $inv->getCount() >= 30 ){
# here code
}
endforeach;

End foreach?

What !!