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# System prepended metadata

title: Session 402 - What's New in Swift
tags: [Swift, WWDC-2019]

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# Session 402 - What's New in Swift

###### tags: `WWDC-2019` `Swift`


https://developer.apple.com/wwdc19/402

- ABI stability
- Module ABI stability
- Swift Package Manager in Xcode
- 包版時會包進 Swift runtime，下載時會自動判斷要不要 thinning，這樣就可以部署到舊版 iOS
- 改善 app launch time
- App size reduced
- Faster bridging between Obj-C and Swift
- `String` 從 UTF-16 改成 UTF-8，大幅改善效能

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- String interpolation
- Implicit return
- Init with partion parameters
- Opaque Result Types
- Property Wrapper Types
- Define Embedded DSLs in Swift