This refers to a pre-release version of Apple’s mobile operating system, specifically a test iteration numbered 18.5, representing the fourth build made available to developers and public testers. Such versions allow for real-world testing of new features and bug fixes before the software is broadly released to the public.
The distribution of these builds enables the identification and resolution of software imperfections that may not be apparent during internal development processes. It provides a means for developers to adapt their applications to function seamlessly with the impending operating system changes. This process, in turn, leads to a more polished and stable user experience upon the official launch.