Branson invests in business card app by Dutch entrepreneur

Richard Branson and rapper Will.i.am are investing in the Knock Knock app, designed by a Dutch entrepreneur.
Business cards, will they survive? According to Dutchman David Wyler they will not. He designed Knock Knock, an app with which you can exchange contact details by simply knocking. For example your Facebook, Snapchat or Twitter profile. The way it works is as follows: you open the app by knocking twice, the app searches for people in the neighbourhood who also use the app, after which you can chat with them or exchange contact details.