iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
iOS 8 and OS X Yosemite May Launch Separately Despite Integration Features
iOS 8 is expected to launch in September alongside the iPhone 6 while OS X Yosemite will not launch until October. Apple used the same release schedule last year, launching iOS 7 alongside the iPhone 5s in September and OS X Mavericks one month later in October.
Continuity allows users to work seamlessly between iPhone, iPad and Mac, with the ability to start emails on one device and easily finish it on another, or using Macs and iPads to answer phone calls and "green bubble" text messages. Because iOS and OS X have never been designed to work better together than with iOS 8 and OS X Yosemite, many saw a dual release as a good opportunity for Apple to cross-promote both its iOS devices and Macs with a stand-out new feature like Continuity.
Apple is planning on using engineering and user interface design members from the iOS team to help complete OS X Yosemite in time for a fall release, with a public beta planned as early as later this month.