While we were looking at Hollywood, Apple put Swift 5 into Xcode
Behind the noise of Apple’s big services announcements, Swift 5 and Xcode 10.2 were released, significant upgrades that should make accelerate app development and distribution.
Swift 5 brings ABI stability
Source-compatible with Swift 4 or later, Swift 5’s flagship feature is the introduction of ABI stability, which means the Swift runtime is now included in macOS, iOS, tvOS, and watchOS. Apple says when you upload apps for sale at the App Store, it “thins the Swift runtime from your apps for faster downloads to devices running the latest OS.”