WWDC19

What's New in Swift - Tuesday

Binary Frameworks

Module + ABI Stability = Binary frameworks
- This allows working with modules compiled in a different compiler than another piece of source code

Reducing swift runtime overhead with shared runtime to %0 when the code is compiled with Swift 5
%10 smaller code size, %15 when Optimize for size is being used
Faster bridging between Swift and Objective-C
Faster NSDictionary to Dictionary bridging
15x faster NSString operations when performed on bridged NSStrings
Native Swift Strings now interoperate with C APIs without overhead. This is possible by moving to UTF-8 from UTF-16.

Implicit return from a single expression
Synthesized default parameters for structs. Ability to construct with selected default parameters only
String interpolation is 1.7x faster than Swift 4.2
- Possibility to use interpolation while localizing a string as well
Opaques result types, to return same concrete types of an instance but hiding them via a protocol to not expose API details to the outside
- var shape: some Shape { }
- Only possible with the new Swift 5.1
Property Wrappers!
- There are property implementation patterns that come up repeatedly. Rather than hardcode a fixed set of patterns into the compiler, we should provide a general "property wrapper" mechanism to allow these patterns to be defined as libraries.
- https://github.com/DougGregor/swift-evolution/blob/property-wrappers/proposals/0258-property-wrappers.md
Define embedded DSLs in Swift to support DSLs with custom DSL builders
- The compiler recognizes the DSL code