Does arcane focus ignore the need for material cost fully?

@ChrisPerkinsDnD does arcane focus ignore the need for material cost fully? Or do you need the item in your pouch?

— TheCardboardCampaign (@CrdboardCampain) July 30, 2016

If you use an arcane focus, you don't need the material components it replaces (see PH, chapter 10). #WOTCstaff https://t.co/sfgRoHHRmO

— (((Chris Perkins))) (@ChrisPerkinsDnD) July 30, 2016