Preview at WWDC likely in June, followed by September launch.
Apple Releases First iOS 9.2.1 Beta for Public Beta Testers
Beta testers who have signed up for Apple's beta testing program will receive the iOS 9.2.1 update over-the-air after installing the proper certificates.
Those who want to be a part of Apple's beta testing program can sign up to participate on the company's beta testing website, which gives users access to both iOS and OS X betas.
The first developer beta of iOS 9.2.1 revealed no significant outward-facing changes, suggesting iOS 9.2.1 is a minor update that will focus on under-the-hood performance improvements and bug fixes to address issues discovered since the release of iOS 9.2.