Apple has updated the multiport adapter, which translates from USB-C to other ports.
There is one USB-C port, one USB-A and one HDMI. The HDMI port has now been adapted to support 4K resolutions at 60 Hz when connected to a device that supports the HDMI 2.0 standard.
- iPad Pro 11
- iPad Pro 12.9 (3rd gen)
- MacBook Pro (15″, 2017 and later)
- iMac (retina 5K, 27″, 2017 and later)
- iMac (retina 4K, 21.5″, 2017 and later)
- iMac Pro (2018)
4K with only 30 Hz are possible via HDMI with the following models:
- MacBook Pro (13″, 2016 and later)
- MacBook Pro (15″, 2016 and later)
- iMac (non-Retina, 21.5″, 2017)
- Mac mini (2018)
The new MacBook Air is not even mentioned. It should output a lower resolution with the adapter, but why it shouldn’t even be able to output 4K at 30 Hz remains questionable.