btw, if you are concerned that Apple is weaning itself of the Chinese supply chain, you really shouldn't be. Even if production gets moved to Vietnam, they are still operated by Chinese companies or FoxConn. It's really hard to beat the low/medium cost manufacturing advantage of Chinese model.
in latest example, BYD built a huge factory for producing glass back cover for iPhones. It uses the latest machines, processes and design and is highly automated. Maybe at some point this gets moved to Vietnam like BYD's iPad production, it's not necessarily a bad thing.