WWDC 2019 What's New in SwiftUI

Shared Swift Runtime for Apps
Binary Frameworks
Apple Swift-Only Frameworks
Package Manager in Xcode
More API Expressibility
Library Evolution

What is ABI?

ABI = "Application Binary Interface"
Specified details of a program's representation at runtime
Compatible ABIs allows separately complied code to interact at runtime

Before ABI stability these both need to be built with the came compiler

ABI stability in Swift 5
Program and framework can be built with different compilers (Swift 5 or later)

What is Module Stability?

Swift libraries and the APIs they export are known as "modules"
Module files are created (and used) by the compiler

Module + ABI stability = Binary frameworks

//WWDC 2019
Binary Frameworks in Swift
Adopting Swift Packages in Xcode
Creating Swift Packages

Apps and the Shared Swift Runtime in the OS

Apps use the runtime from OS when it is available
Apps that backward deploy contain a runtime copy
·Embedded runtime copy is inert on OSs with shared runtime
·iOS AppStore thins out runtime copy when downloading to iOS 12.2 or later

Launch time overhead with Swift 5 = 0%

Faster Bridging Between Swift and Objective-C

NSDictionary to Dictionary Bridging 1.6x faster
NSString operations when performed on bridged Swift Strings 15x faster

Native Swift Strings now interoperate with C APIs without overhead
Small Strings include Unicode characters in addition to ASCII
Fast Interoperability with NSString

SwiftNIO

Swift Sourcekit

Language and Standard Library

在SwiftUI的Text可以自动实现国际化

@propertyWrapper

Wrapper types define custom access patterns
Property can adopt by adding an attribute to its declaration

Define Embedded DSLs in Swift

html {
    head {
        title(...)
    }
    body {
        h2 { ... }
        br()
        "....."
        a {
            "..."
        }.href("http...")
        //还可以用Swift的控制  
        if !loggedIn {
            button {
                ...
            }
            .onclick("")
        }
    }
}