ABI stability Module stability So different components can be built by different compiler versions You can distribute binary frameworks for others to use
Swift packages more tightly integrated
Shared swift runtime improves performance of applications Shared runtime will still be included if building for backwards compatibility iOS app store will thin this out on downloads Apps will use the system runtime if availible Faster launch time
Strings changed from UTF16 to UTF8 Swift c interop without overhead 20% more http requests with SwiftNIO after change to utf8
Open source technologies Swift official docker images SourceKit Language server protocol coming in the future. github.com/apple/sourcekit-lsp
Support for SIMD, “single instruction multiple data” Redesigned string interpolation, with custom interpolators
Opaque result types, ie “some Shape” Property wrapper types, reduces code repetition declaring computed properties
Define embedded DSLs in swift. Domain specific language, ie HTML This is used to power the declarive syntax of SwiftUI as well