Apple analyst Ming-Chi Kuo released a note indicated he believes Apple will release VR glasses in 2020.
Apple has been rumoured to be working on virtual reality and augmented reality since 2017. They have released ARKit 2 with iOS 12 which introduced multi user augmented reality.

Google has been trying for years to popularise its Google Glasses for a few years now with little success.
The new Apple VR glasses will be designed to work with Apple iPhone rather than be a standalone accessory. By utilising the iPhone they will be able to stay slim and light unlike some of the more bulky competitors.

Rumours suggest that Apple will spin off a custom iOS version tentatively labelled rOS. rOS reportedly stands for Reality Operating System.