Yesterday, developer Andrew Wiik shared a few screenshots of what appears to be an early form of Dark Mode running on the first beta of iOS 10 inside Xcode. Wiik's tweet shows darkened versions of Messages, while a responding user corroborated his finding with pictures of Clock, Safari, and iTunes.
The Clock app is known to have gotten a darkened redesign in iOS 10, and a shot of iBooks is also included, but a reading-enabled "Night Mode" has been around since iOS 8. iTunes also presently uses a darkened scheme in its iOS app but, according to beta tester Mac Aficionados on Twitter, the system wide Dark Mode provides a unified darkened hue across all apps in comparison to what used to be an app-specific colorway with varying levels of black.
In a Reddit post sharing the screenshots, Wiik mentioned that "Apple has implemented the feature it just isn't available for us users yet." He went on to hope that "this won't be an iPhone 7 exclusive."
The potential for Dark Mode's inclusion in iOS has been around for a while now, but picked up steam thanks to speculation in a few concept videos shared earlier in the Spring. Closer to WWDC, possible hints from a few evasive Siri responses -- alongside additional concept images -- fueled more rumors than ever that the feature would be announced by Apple during its keynote.