https://www.theverge.com/2018/6/2/17420584/macos-10-14-dark-mode-apple-news-app-wwdc-2018

Apple’s Worldwide Developers Conference is almost here, and the company is expected to unveil updates for its iOS, macOS, tvOS, and watchOS operating systems. Apple appears to have accidentally leaked one upcoming feature coming to macOS 10.14: a dark mode.

Developer Steve Troughton-Smith‏ discovered a 30-second preview video that shows the development software operating in a dark mode, and he tweeted several screenshots of the upcoming Xcode 10 showing off the setting.