"What's new in Swift"の要約 / swift_5_9_summary

集まれSwift好き！Swift愛好会スピンオフ WWDC23セッション要約会 @ DeNA
https://love-swift.connpass.com/event/281287/

## 参考リンク

- What's new in Swift - WWDC23 - Videos - Apple Developer
https://developer.apple.com/videos/play/wwdc2023/10164/

- Swift 5.9 チェンジログ
https://github.com/apple/swift/blob/main/CHANGELOG.md#swift-59

- SE-0380: `if` and `switch` expressions
https://github.com/apple/swift-evolution/blob/main/proposals/0380-if-switch-expressions.md

- SE-0389: Attached Macros
https://github.com/apple/swift-evolution/blob/main/proposals/0389-attached-macros.md

- Observable
https://developer.apple.com/documentation/observation/observable-swift.macro

- SE-0397: Freestanding Declaration Macros
https://github.com/apple/swift-evolution/blob/main/proposals/0397-freestanding-declaration-macros.md

- SE-0398: Allow Generic Types to Abstract Over Packs
https://github.com/apple/swift-evolution/blob/main/proposals/0398-variadic-types.md

- buildBlock()
https://developer.apple.com/documentation/swiftui/viewbuilder/buildblock()

- SE-0395: Observation
https://github.com/apple/swift-evolution/blob/main/proposals/0395-observability.md

- SE-0390: Noncopyable structs and enums
https://github.com/apple/swift-evolution/blob/main/proposals/0390-noncopyable-structs-and-enums.md

Transcript

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   w ͱ͖Ͳ͖4XJGUѪ޷ձͷ
   

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3. ͷ৽ػೳʹ͍ͭͯ࿩͠·͢
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4. 4&
   JGࣜͱTXJUDI͕ࣜ௥Ճ͞Εͨ
   // Swift 5.8
   
   
   let isUhooi = {
   
   
   switch monster {
   
   
   case .uhooi:
   
   
   return true
   
   
   case .chibird:
   
   
   return false
   
   
   }
   
   
   }()
   // Swift 5.8
   
   
   let foo = {
   
   
   if bar == 0 {
   
   
   return "Foo"
   
   
   } else {
   
   
   return "Bar"
   
   
   }
   
   
   }()
   

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5. 4&
   JGࣜͱTXJUDI͕ࣜ௥Ճ͞Εͨ
   // Swift 5.9
   
   
   let isUhooi =
   
   
   switch monster {
   
   
   case .uhooi: true
   
   
   case .chibird: false
   
   
   }
   // Swift 5.9
   
   
   let foo =
   
   
   if bar == 0 {
   
   
   "Foo"
   
   
   } else {
   
   
   "Bar"
   
   
   }
   

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6. 4&
   "UUBDIFE.BDSPT͕௥Ճ͞Εͨ
   // Swift 5.9
   
   
   import Observation
   
   
   @Observable
   
   
   final class MonsterViewModel {
   
   
   var name = ""
   
   
   var description = ""
   
   
   
   
   init(name: String, description: String) {
   
   
   self.name = name
   
   
   self.description = description
   
   
   }
   
   
   }
   

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7. 4&
   'SFFTUBOEJOH%FDMBSBUJPO.BDSPT͕௥Ճ͞Εͨ
   // Swift 5.9
   
   
   import PowerAssert
   
   
   let a = -1
   
   
   let b = 10
   
   
   let c = 17
   
   
   #assert(max(a, b) == c)
   
   
   | | | | |
   
   
   10 -1 10 | 17
   
   
   false
   
   
   

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8. 4&
   Մม௕ͷܕΛந৅ԽͰ͖Δ
   // Swift 5.8
   
   
   static func buildBlock(
   
   
   _ c0: C0,
   
   
   _ c1: C1,
   
   
   _ c2: C2,
   
   
   _ c3: C3,
   
   
   _ c4: C4,
   
   
   _ c5: C5,
   
   
   _ c6: C6,
   
   
   _ c7: C7,
   
   
   _ c8: C8,
   
   
   _ c9: C9
   
   
   ) -> TupleView<(C0, C1, C2, C3, C4, C5, C6, C7, C8, C9)> where C0 : View, C1 : View, C2 :
   View, C3 : View, C4 : View, C5 : View, C6 : View, C7 : View, C8 : View, C9 : View {
   
   
   TupleView((c0, c1, c2, c3, c4, c5, c6, c7, c8, c9))
   
   
   }
   

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9. 4&
   Մม௕ͷܕΛந৅ԽͰ͖Δ
   // Swift 5.9
   
   
   static func buildBlock(_ content: repeat each Content)
   
   
   -> TupleView<(repeat each Content)> where repeat each Content : View {
   
   
   TupleView((repeat each content))
   
   
   }
   

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10. 4&
    $PNCJOFʹґଘͤͣ؂ࢹͰ͖Δ
    // Swift 5.8
    
    
    import Combine
    
    
    final class MonsterViewModel: ObservableObject {
    
    
    @Published var name: String
    
    
    @Published var description: String
    
    
    
    
    init(name: String, description: String) {
    
    
    self.name = name
    
    
    self.description = description
    
    
    }
    
    
    }
    
    
    struct MonsterView: View {
    
    
    @StateObject var viewModel: MonsterViewModel = .init(name: "Uhooi", description: "Foo")
    
    
    
    
    var body: some View {
    
    
    Text("Hello, \(viewModel.name)")
    
    
    }
    
    
    }
    

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11. 4&
    $PNCJOFʹґଘͤͣ؂ࢹͰ͖Δ
    // Swift 5.9
    
    
    import Observation
    
    
    @Observable
    
    
    final class MonsterViewModel {
    
    
    var name = ""
    
    
    var description = ""
    
    
    
    
    init(name: String, description: String) {
    
    
    self.name = name
    
    
    self.description = description
    
    
    }
    
    
    }
    
    
    struct MonsterView: View {
    
    
    var viewModel: MonsterViewModel = .init(name: "Uhooi", description: "Foo")
    
    
    
    
    var body: some View {
    
    
    Text("Hello, \(viewModel.name)")
    
    
    }
    
    
    }
    

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12. 4&
    TUSVDUͱFOVNΛίϐʔෆՄೳʹ͢Δ
    // Swift 5.8
    
    
    struct S {
    
    
    init() {
    
    
    print("S: init()")
    
    
    }
    
    
    
    
    // ❌: Deinitializers may only be declared within a class or actor
    
    
    deinit {
    
    
    print("S: deinit")
    
    
    }
    
    
    }
    

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13. 4&
    TUSVDUͱFOVNΛίϐʔෆՄೳʹ͢Δ
    // Swift 5.9
    
    
    struct S: ~Copyable {
    
    
    init() {
    
    
    print("S: init()")
    
    
    }
    
    
    
    
    // ✅
    
    
    deinit {
    
    
    print("S: deinit")
    
    
    }
    
    
    }
    

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14. ·ͱΊ
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    w 0CTFSWBUJPO
    w 4XJGU'PVOEBUJPO
    

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