Apple has seeded the fourth batch of developer betas for iOS 11.4, macOS 10.13.5, tvOS 11.4, and watchOS 4.3.2.
The code is available to developers via over-the-air updates or through the Apple Developer Center. Beta releases for the public are usually provided a few days after developer seeds.
The fourth iOS 11.4 beta has build number 15F5071a. The previous beta release had two build numbers: 15F4061d and 15F4061e.
Support for the ClassKit framework features in iOS 11.4, to allow developers to make their educational apps work with Apple's school-based software. Using the upcoming Schoolwork app, teachers can add links that takes students to specific parts of another app for an assignment, with ClassKit enabling the links to function.
Apple is also reintroducing support for Messages in iCloud, a feature that synchronized conversations between multiple Apple devices logged into the same Apple ID account, using Apple's cloud infrastructure. Messages in iCloud was set to be included as part of iOS 11, but while it has appeared in betas, the feature has yet to be made available as part of a full public iOS release.
The latest beta of tvOS 11.4 bears the build number 15L5570a. For the third beta, the build was 15L5560b.
Both iOS 11.4 and tvOS 11.4 betas include support for AirPlay 2, Apple's upcoming wireless streaming protocol that will replace AirPlay, adding features like multi-room audio. Like Messages in iCloud, Apple previously tested the protocol in the beta for iOS 11.3, but removed the functionality ahead of the final public release.
macOS High Sierra 10.13.5's fourth beta has the build number 17F66a, up from the previous build of 17F59b.
So far, the main addition to 10.13.5 has been support for Messages in iCloud, with few other visible changes to the operating system. The minor change in version number suggests it to be a smaller release with few extra features, largely concentrating on improving performance and squashing bugs.
In macOS 10.13.4, released on March 29, Apple introduced enhanced eGPU support, making it easier for user to connect a separate Thunderbolt 3 enclosure containing a dedicated video card to a Mac. This increases the available processing power for graphics-heavy tasks, such as gaming, VR, and CAD.
The release also added Business Chat, which lets users communicate directly with businesses via Messages, and make purchases of goods or services at the same time. The update further included changes to how Safari sorts bookmarks, and more clarity on privacy and personal data.
The fourth beta of watchOS 4.3.1 has the build number 15T5565a, whereas the third beta was build 15T5555c.
Apple has started to advise Apple Watch wearers that old apps will not be supported in "future versions" of watchOS using a notification added since the first beta.
AppleInsider is currently testing out the new code to find out what changes have been introduced, if any.
AppleInsider, and Apple itself, strongly advise against installing beta releases on mission-critical hardware, due to the potential loss of data. Use secondary devices for beta testing, where available, and keep backups of any important data before installation or updating the software.