Apple has already begun rolling out the fourth build for three different firmwares. The first is iOS 10.3, which can be downloaded by both registered developers, as well as public beta testers. The new beta build brings a few new features the Find My AirPods option within the Find My iPhone app, Wi-Fi Calling for iCloud connected devices on Verizon, and a new notification that alerts users that 32-bit apps can't run properly (suggesting they may not run at all as of iOS 11. WatchOS beta 3.2 also has a few new features like a proper theater mode, something that the Apple watch had...
Source: http://www.gsmarena.com/apple_releases_beta_4_for_ios_103_watchos_32_and_macos_sierra_10124-news-23690.php
