How get Facebook profile ID (uid) when using vanity URL

When You are working with facebook apps, you do need sometimes to add administrators or moderators to Your application. If selected person is not in Your friend list, You cannot add him to the list using auto-suggest box. Thats the moment, when You will need to know user`s facebook profile id (uid). Real problem is coming when user is using Facebook vanity URL for his/her profile (like www.facebook.com/some.selected.vanity.url). Continue reading