Apple released 10.10.3 to developers today, offering up the first release of Photos for Mac, the long-awaited replacement for iPhoto. It's not available publicly yet — only to registered developers and others with access to Apple's development builds of OS X Yosemite, at this hour. But something's caught the eye of developers who have downloaded it. Jason Snell, writing for Six Colors:

Today Apple dropped Photos for Mac via a developer release, and some developers are reporting signs that Apple has built this new app using something called UXKit, which sits above the Mac's familiar AppKit frameworks and strongly resembles UIKit on iOS.

UIKit is a programming framework in iOS that helps developers manage an iOS app's user interface, user input and manage interaction with the system. UIKit hasn't existed on the Mac, which makes it more difficult for developers already invested in iOS to bring their products to the Mac.

UXKit may be Apple's attempt to bridge that gap. If so, it'd be a big step towards simplifying the approach of writing applications that will run on iOS and Mac.