Just after Apple came out with iOS 8.3 beta 2 for developers, Apple seeded OS X Yosemite 10.10.3 Developer Preview 2 for Mac developers and also a new Xcode beta.
This version comes with more bug fixes and overall improvements, and also the new diversified Emoji feature. The new Emoji feature enables you to change the skin tones and the look of the Emojis when you send a message, for example.
OS X Yosemite 10.10.3 Developer Preview 2 can be downloaded by developers who already have the OS X Yosemite 10.10.3 beta on their Mac from the Updates tab in the Mac App Store. Else, developers can go to Apple’s Developer Portal to get the beta version.