For a while, iOS developers have complained that the UIKit framework they use to develop apps isn’t available on the Mac, making it harder to apply the same tools and techniques and code they build for iOS to Mac apps.
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.
More from the legendary Steven Troughton-Smith:
It’s still mostly all AppKit, but with a UIKit-like API shim. I’m guessing Photos for Mac builds out of the same project tree as iOS
UXKit has navigation controllers, tab bar controllers, table view controllers, toolbars & tintColor support
Maybe someday we’ll program apps simply to ‘UXKit’ and it will map to AppKit or UIKit under the hood.