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Whats new in swift

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Version 5.9

  • Open source workgroups update
    • Vision documents are collections of themed proposals
  • if/else & switch used as expressions
    • Can replace complex ternary expressions with easier to read if/elseif/else statements, used as the assignment
  • Better errors in SwiftUI
  • Variable length arguments in generics
    • <each Result> type parameter packs.
    • Used for functions that want to accept variable length args of a generic type, when each corresponds to a specific return type.
  • Macros
    • Distributed as packages
    • Defined like public macro assert(_ condition: Bool) = #externalMacro(...)
    • Written as a compiler extension that takes in the source code and returns a resulting expanded code.
    • Freestanding macros can be used everywhere
    • Attached macros work like property wrappers, with @
    • Can inspect macro generated code, and debug into it
      • Right click, “expand macro”
      • Errors will auto expand
    • Different types of attached macros to declare what level the new code goes in, such as members, peers, etc.
    • @Observable class macro adds Published to every member, and then also takes care of declaring it as ObservedObject when used in a view.
      • This uses three separate macros under the hood.
  • Swift on low level systems
    • Open sourced the re-write of Foundation in swift
    • Converting C and objC to swift
    • Will be the single shared apple and non apple version of foundation
    • Significant performance improvements
  • Type ownership
    • Copyable by default, of course
    • struct FileDescriptor: ~Copyable {} marks a struct as Not-Copyable
      • You can then include a deinit method.
      • You can add consuming functions, which make the object unusable
  • C++ interop
    • Swift understands common c++ idioms
      • May sometimes need annotations to help swift understand
    • Works in both directions
    • Swift will produce a generated header
    • Dont need to use an equivalent of @objc, most swift types will just work
    • Cmake
      • Worked with cmake team to add swift as a langauge option
      • Can include cpp and swift together
  • What’s new in swift concurrency
    • Custom actor executors, to implement the queue processing for tasks
    • Conform to the SerialExecutor protocol