This is kinda complicated as a custom field could be attached to something else than a post type. It can be attached to a specific page, a taxonomy or a lot of other things. In fact it is attached to all the posts which correspond to the type of object(s) you attach the custom field.
That’s why (I think) the get_field_object() requires at least one $post_id to be found.
I was just looking for the same function. This will be very helpful.
The plugin from mcguffin hasn’t been commited since november and there is some todo list which make me think this is an abandoned project :/
