On Tuesday, Apple released the first beta of iOS 9.2 to developers, along with a warning that upgrading to the new release will prevent those devices from being downgraded to any previous version. The new build, numbered 13C5055d, comes less than a week after the release of iOS 9.1 -- which introduced support for Unicode 8, and sported enhancements to Live Photos on the new iPhones among other tweaks. In addition, Apple updated its beta of Xcode to version 7.2 to support the various new OS versions and devices.
