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SwiftUI を理解するために必要な Swift 5.1 の新機能 (some View編)

SwiftUI を理解するために必要な Swift 5.1 の新機能 (some View編)

kumamotone

August 07, 2019
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  1. • iOS/AndroidΤϯδχΞ • Yahoo!ΧϨϯμʔ iOS։ൃ • ษڧձӡӦ • Bonfire iOSɺWWDC

    Extended ͳͲ • ϚΠϒʔϜ • ఱؾͷࢠ ۽ຊ ࿨ਖ਼ (@kumamo_tone)
  2. • ࠓ೔͸ SwiftUI ͷίʔυΛಡΈॻ͖͢Δ্Ͱ
 ஌͓ͬͯ͘ͱྑ͍Swift 5.1ͷ৽ػೳʹ͍ͭͯ • Implicit return from

    single expressions • Function Builder • Opaque Result Type • ૝ఆର৅ऀ • ؾܰʹཧղ͍ͨ͠ • SwiftUI ؾʹͳͬͯ͸͍Δ͚Ͳ͋·ΓखΛ෇͚Ε͍ͯͳ͍ TL;DR
  3. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } }
  4. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } public protocol View { associatedtype Body : View var body: Self.Body { get } } 7JFXϓϩτίϧͷ͜ͱ 7JFXϓϩτίϧͷఆٛ
  5. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } public protocol View { associatedtype Body : View var body: Self.Body { get } } 7JFXϓϩτίϧͷ͜ͱ 7JFXϓϩτίϧͷఆٛ ٙ໰
  6. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } TPNFͬͯԿʁ͆
  7. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } TPNFͬͯԿʁ͆ ͜ͷதͰ͸ Կ͕ߦΘΕ͍ͯΔʁ
  8. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } SFUVSOͲ͜ʹߦͬͨʁ ͜ͷதͰ͸ Կ͕ߦΘΕ͍ͯΔʁ TPNFͬͯԿʁ͆
  9. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } SFUVSOͲ͜ʹߦͬͨʁ ʁ TPNFͬͯԿʁ͆ ͜ͷதͰ͸ Կ͕ߦΘΕ͍ͯΔʁ
  10. Swift5.1ʹ௥Ճ͞Εͨɺ3ͭͷ৽ػೳʹΑͬͯઆ໌Ͱ͖Δ • Swift Evolution: SE-0255 • Implicit return from single

    expressions • Swift Evolution: SE-XXXX • Function builders • Swift Evolution: SE-0244 • Opaque Result Type Swift5.1ͷ৽ػೳ ͻͱͭΊʂ
  11. SE-0255: Implicit return from single expressions • ϝϦοτ • ͖ͬ͢Γ͢Δ

    ΫϩʔδϟͰ͸લ͔Βɺ͕ࣜͻͱ͔ͭ͠ͳ͍ͱ͖returnΛলུͰ͖ͨ let names = persons.map { $0.name }
  12. SE-0255: Implicit return from single expressions struct Rectangle { var

    width = 0.0, height = 0.0 var area: Double { width * height } } ؔ਺΍ Computed Property Ͱ΋OK ΫϩʔδϟͰ͸લ͔Βɺ͕ࣜͻͱ͔ͭ͠ͳ͍ͱ͖returnΛলུͰ͖ͨ • ϝϦοτ • ͖ͬ͢Γ͢Δ let names = persons.map { $0.name }
  13. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } }
  14. struct ContentView: View { var body: some View { return

    VStack { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } SFUVSO͕লུ͞Ε͍ͯͨ
  15. • Swift Evolution: SE-0255 • Implicit return from single expressions

    • Swift Evolution: SE-XXXX • Function builders (draft proposal) • Swift Evolution: SE-0244 • Opaque Result Type Swift5.1ͷ৽ػೳ ;ͨͭΊʂ
  16. • վߦ۠੾Γͷཁૉ͔ͨͪΒɺม਺એݴͱؔ਺ݺͼग़͠Λੜ੒͢Δ • @_functionBuilderΛ͚ͭͨstruct͸ɺFunction builderʹͳΔ SE-XXXX: Function Builders // @TupleBuilder͸

    // @_functionBuilderͱͯ͠Ͳ͔͜Ͱఆٛ @TupleBuilder func build() -> (Int, Int, Int) { 1 2 3 } func build() -> (Int, Int, Int) { let _a = 1 let _b = 2 let _c = 3 return TupleBuilder .buildBlock(_a, _b, _c) } ίϯύΠϥ͕ม׵
  17. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } ఆٛΛݟΔ
  18. public struct VStack<Content> : View where Content : View {

    @inlinable public init(
 alignment: HorizontalAlignment = .center, spacing: CGFloat? = nil, @ViewBuilder content: () -> Content) public typealias Body = Never } ఆٛΛݟΔ
  19. @_functionBuilder public struct ViewBuilder { public static func buildBlock<Content> (_

    content: Content) -> Content where Content : View } Ҿ਺1ݸͰɺͦΕͱಉ͡ܕͷViewΛฦ͍ͯ͠Δ
  20. extension ViewBuilder { public static func buildBlock<C0, C1> (_ c0:

    C0, _ c1: C1) -> TupleView<(C0, C1)> where C0 : View, C1 : View } Ҿ਺2ݸͰɺͦΕͱಉ͡ܕͷTupleView<(C0, C1)>Λฦ͍ͯ͠Δ
  21. extension ViewBuilder { public static func buildBlock<C0, C1> (_ c0:

    C0, _ c1: C1) -> TupleView<(C0, C1)> where C0 : View, C1 : View } Ҿ਺2ݸͰɺͦΕͱಉ͡ܕͷTupleView<(C0, C1)>Λฦ͍ͯ͠Δ ʹ74UBDLͷҾ਺ͷਖ਼ମ
  22. extension ViewBuilder { public static func buildBlock<C0, C1, C2>(_ c0:

    C0, _ c1: C1, _ c2: C2) -> TupleView<(C0, C1, C2)> where C0 : View, C1 : View, C2 : View } 3ݸ൛
  23. extension ViewBuilder { public static func buildBlock<C0, C1, C2, C3>(_

    c0: C0, _ c1: C1, _ c2: C2, _ c3: C3) -> TupleView<(C0, C1, C2, C3)> where C0 : View, C1 : View, C2 : View, C3 : View } 4ݸ൛…
  24. extension ViewBuilder { public static func buildBlock<C0, C1, C2, C3,

    C4, C5, C6, C7, C8, C9>(_ 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 } 10ݸ൛·Ͱ͋Δ
  25. extension ViewBuilder { public static func buildBlock<C0, C1, C2, C3,

    C4, C5, C6, C7, C8, C9>(_ 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 } 10ݸ൛·Ͱ͋Δ ʹ10ݸ൛·Ͱ͔͠ͳ͍ ͦΕҎ্ฒ΂͍ͨͱ͖͸ɺ GroupΛ࢖͏͜ͱ
  26. struct ContentView: View { var body: some View { return

    VStack { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } ͭ·Γ͜ͷϒϩοΫ͸
  27. struct ContentView: View { var body: some View { return

    VStack { return ViewBuilder.buildBlock( Text(item.title), Text(item.subtitle) .foregroundColor(Color.gray) } } } } ͜͏ղऍ͞ΕΔ
  28. ฦΓ஋ͷܕ͸ $5FYU $5FYUͳͷͰɺ 5VQMF7JFX 5FYU 5FYU ʹͳΔ struct ContentView: View

    { var body: some View { return VStack { return ViewBuilder.buildBlock( Text(item.title), Text(item.subtitle) .foregroundColor(Color.gray) } } } }
  29. ฦΓ஋ͷܕ͸ɺ74UBDLͷܕύϥϝʔλ$POUFOUʹΑͬͯ 74UBDL5VQMF7JFX 5FYU 5FYU ʹͳΔ struct ContentView: View { var

    body: some View { return VStack { return ViewBuilder.buildBlock( Text(item.title), Text(item.subtitle) .foregroundColor(Color.gray) } } } }
  30. @_functionBuilder public struct NumsBuilder { public static func buildBlock(_ nums:

    Int...) -> [Int] { nums } } func printNums(@NumsBuilder numsBuilder: () -> [Int]) { numsBuilder().forEach { print($0) } } printNums { 1 2 3 } ࣗ෼Ͱͭ͘Δ͜ͱ΋Ͱ͖Δ
  31. • Swift Evolution: SE-0255 • Implicit return from single expressions

    • Swift Evolution: SE-XXXX • Function builders (draft proposal) • Swift Evolution: SE-0244 • Opaque Result Type Swift5.1ͷ৽ػೳ ͍͞͝ʂ
  32. • δΣωϦΫεͷΑ͏ͳ΋ͷ • some Protocol ͷΑ͏ͳܕ͕ Opaque Result Type •

    some View ͸
 ʮ۩ମతͳܕ͸ެ։͠ͳ͍͚ͲɺViewϓϩτίϧʹద߹ͨ͠ԿΒ͔ͷܕʯ
 Ͱ͋Δ͜ͱΛද͢ SE-0244: Opaque Result Type
  33. struct ContentView: View { var body: some View { return

    VStack { return ViewBuilder.buildBlock( Text(item.title), Text(item.subtitle) .foregroundColor(Color.gray) ) } } } 74UBDL5VQMF7JFX 5FYU 5FYU  ͷ࣮ࡍͷܕ͸ɺ ͨͱ͑͹ɺTPNF7JFX ͕ͩɺ֎ଆ͔Βݟͨͱ͖͸7JFXͱͯ͠ৼΔ෣͏
  34. struct ContentView: View { var body: VStack<TupleView<(Text, Text)>> { return

    VStack ( return ViewBuilder.buildBlock( Text(item.title), Text(item.subtitle) .foregroundColor(Color.gray) ) } } } ۩ମܕΛࢦఆͯ͠΋0,
  35. struct ContentView: View { var body: VStack<TupleView<(Text, Text)>> { return

    VStack ( return ViewBuilder.buildBlock( Text(item.title), Text(item.subtitle) .foregroundColor(Color.gray) ) } } } ۩ମܕΛࢦఆͯ͠΋0, ͜ͷܗͳΒɺ΋͸΍4XJGUະຬͷจ๏Ͱ΋ҙຯ͕௨Δ
  36. SE-0244: Opaque Result Type func map<A, B>(l: List<A>, _ f:

    A -> B) -> List<B> { switch l { case .Nil: return .Nil case let .Cons(x, xs): return cons(f(x), map(xs, f)) } } [1,2].map { $0 * 2 } δΣωϦΫεͷܕ͸
 ֎ଆ͔Β࣮ࡍͷܕΛ
 ࢦఆͯ֬͠ఆ͢Δ Opaque Result Type Ͱ͸
 ಺ଆ͔Β࣮ࡍͷܕ͕֬ఆ͢Δ *OU*OU struct ContentView: View { var body: some View { VStack { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } 74UBDL 5VQMF7JFX 5FYU 5FYU 
  37. struct ContentView: View { var body: View { VStack {

    Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } 7JFX͸QSPUPDPMͰɺ BTTPDJBUFEUZQFΛ΋ͭͷͰɺ ͜͏͸ॻ͚ͳ͍
  38. struct ContentView: View { var body: AnyView { AnyView(VStack {

    Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) }) } } ܕফڈ͸Ͱ͖Δ͕ɺ ύϑΥʔϚϯεϩε͕͋Δ
  39. • Swift Evolution: SE-0255 • Implicit return from single expressions

    • Swift Evolution: SE-XXXX • Function builders (draft proposal) • Swift Evolution: SE-0244 • Opaque Result Type Swift5.1ͷ৽ػೳ
  40. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } SFUVSO͸ ࣜͭͳΒলུՄೳ
  41. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } SFUVSO͸ ࣜͭͳΒলུՄೳ 'VODUJPO#VJMEFSʹΑͬͯɺ 7JFX#VJMEFSCVJME#MPDL 5FYU 5FYU ͱղऍ͞ΕΔ ࣮ࡍͷܕ͸ɺ74UBDL5VQMF7JFX 5FYU 5FYU 
  42. struct ContentView: View { var body: some View { VStack

    { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) } } } TPNF7JFX͸ 7JFXʹద߹͢Δ ԿΒ͔ͷܕͰ͋Δ͜ͱΛࣔ͢ 'VODUJPO#VJMEFSʹΑͬͯɺ 7JFX#VJMEFSCVJME#MPDL 5FYU 5FYU ͱղऍ͞ΕΔ ࣮ࡍͷܕ͸ɺ74UBDL5VQMF7JFX 5FYU 5FYU  SFUVSO͸ ࣜͭͳΒলུՄೳ
  43. SwiftUI ͸Swift5.1ͷػೳʹΑ͖ͬͯͬ͢Γॻ͚ΔΑ͏ʹͳ͍ͬͯΔ • Swift Evolution: SE-0255 • Implicit return from

    single expressions • Swift Evolution: SE-XXXX • Function builders • Swift Evolution: SE-0244 • Opaque Result Type ·ͱΊ
  44. • SwiftUIͷຐ๏Λ࣮ݱ͢Δ࢓૊Έ (Custom Attributes, Function Builder) • https://qiita.com/kentrino/items/dc6e77a0ddd21187cc55 • SwiftUIͷίʔυΛಡΈղ͘

    • https://blog.personal-factory.com/2019/06/07/understand-swiftui-code/ • Swift 5.1 ʹಋೖ͞ΕΔ Opaque Result Type ͱ͸Կ͔ • https://qiita.com/koher/items/338d2f2d0c4731e3508f • Opaque Result Typeͷղઆ • https://qiita.com/omochimetaru/items/f13fe3e54fab01648ba4 See Also