Homekit support coming in 2018!
It's official! Weiwei has confirmed that Yeelight is working on bringing homekit support to ALL devices (Not including non-WiFi devices). Homekit support might will arriving via a software update of some sort to the Yeelight app.
Homebridge - http://bit.ly/2GL4p4a
Homebridge-yeelight - http://bit.ly/2EvBhf8
Apple Homekit - https://apple.co/2JsB7Je
UPDATE 14/02/18 Yeelight is working on an software update for all devices to allow for Homekit support straight from the app.
However this may take months. It may come out by the end of 2018
UPDATE 01/04/18 WeiWei has said Homekit development is ongoing. They are running WiFi certification and need to submit an application to Apple, which is harder than getting homekit to actually work.
The current estimated Homekit release date is 4-5 months
UPDATE 08/04/18 On Banggood's product page for the new Colour Bulb v2, It states that the product supports "Apple Homekit", however it currently doesn't support it my knowledge and should be coming soon. Stay tunes for more information.
We will have to wait and see how Yeelight will impelement Homekit in their products