Shortly after the release of iOS 11 public beta 2, Mac users also received a second pre-release build of macOS High Sierra, available for public testing ahead of its arrival this fall.
Participation in Apple's public beta system is free after registering and agreeing to terms and conditions at the company's website. Participants can test out pre-release builds of macOS, iOS and tvOS, though watchOS is not a part of the program.
In the latest High Sierra beta, Apple enabled initial Time Machine support, and has added routines to AVKit for developers to allow users additional flexibility for content playback when multiple outputs are available. Additionally, some touch event processing modifications have been implemented, with enhanced timing for ignoring errant touches.
The second pre-release beta of macOS High Sierra arrives a few weeks after the first build was provided in late June.
Apple recommends that users install the software only on a secondary Mac, and make a backup of that device beforehand.
High Sierra is due to launch as a free update this fall. The software will support standards like Metal 2 and H.265/HEVC video, and transition to the Apple File System, already in use on iOS 10.3.x devices. Apple is also planning miscellaneous upgrades to apps like Photos, Mail, and Safari.
By spring 2018, High Sierra will also officially support external Thunderbolt 3 GPUs, enabling high-level graphics normally reserved for gaming PCs and workstations.