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

Slide 1

Slide 1 text

SwiftUI Λཧղ͢ΔͨΊʹඞཁͳ Swift 5.1 ͷ৽ػೳ (some Viewฤ) 2019/08/07 Bonﬁre iOS #6 twitter.com/kumamo_tone

Slide 2

Slide 2 text

• iOS/AndroidΤϯδχΞ • Yahoo!ΧϨϯμʔ iOS։ൃ • ษڧձӡӦ • Bonﬁre iOSɺWWDC Extended ͳͲ • ϚΠϒʔϜ • ఱؾͷࢠ ۽ຊ ࿨ਖ਼ (@kumamo_tone)

Slide 3

Slide 3 text

• 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

Slide 4

Slide 4 text

No content

Slide 5

Slide 5 text

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

Slide 6

Slide 6 text

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

Slide 7

Slide 7 text

Slide 8

Slide 8 text

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

Slide 9

Slide 9 text

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

Slide 10

Slide 10 text

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

Slide 11

Slide 11 text

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

Slide 12

Slide 12 text

" Magic?

Slide 13

Slide 13 text

" No.

Slide 14

Slide 14 text

Swift5.1ʹ௥Ճ͞Εͨɺ3ͭͷ৽ػೳʹΑͬͯઆ໌Ͱ͖Δ • Implicit return from single expressions • Function builders • Opaque Result Type Swift5.1ͷ৽ػೳ

Slide 15

Slide 15 text

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

Slide 16

Slide 16 text

Implicit return from single expressions

Slide 17

Slide 17 text

SE-0255: Implicit return from single expressions • ϝϦοτ • ͖ͬ͢Γ͢Δ ΫϩʔδϟͰ͸લ͔Βɺ͕ࣜͻͱ͔ͭ͠ͳ͍ͱ͖returnΛলུͰ͖ͨ let names = persons.map { $0.name }

Slide 18

Slide 18 text

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 }

Slide 19

Slide 19 text

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

Slide 20

Slide 20 text

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

Slide 21

Slide 21 text

• 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

Slide 22

Slide 22 text

Function builders (draft proposal)

Slide 23

Slide 23 text

• վߦ۠੾Γͷཁૉ͔ͨͪΒɺม਺એݴͱؔ਺ݺͼग़͠Λੜ੒͢Δ • @_functionBuilderΛ͚ͭͨؔ਺͸ɺFunction builderʹͳΔ SE-XXXX: Function Builders

Slide 24

Slide 24 text

• 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׵

Slide 25

Slide 25 text

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

Slide 26

Slide 26 text

public struct VStack : View where Content : View { @inlinable public init(  alignment: HorizontalAlignment = .center, spacing: CGFloat? = nil, @ViewBuilder content: () -> Content) public typealias Body = Never } ఆٛΛݟΔ

Slide 27

Slide 27 text

@_functionBuilder public struct ViewBuilder { public static func buildBlock (_ content: Content) -> Content where Content : View } Ҿ਺1ݸͰɺͦΕͱಉ͡ܕͷViewΛฦ͍ͯ͠Δ

Slide 28

Slide 28 text

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

Slide 29

Slide 29 text

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

Slide 30

Slide 30 text

extension ViewBuilder { public static func buildBlock(_ c0: C0, _ c1: C1, _ c2: C2) -> TupleView<(C0, C1, C2)> where C0 : View, C1 : View, C2 : View } 3ݸ൛

Slide 31

Slide 31 text

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

Slide 32

Slide 32 text

extension ViewBuilder { public 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 } 10ݸ൛·Ͱ͋Δ

Slide 33

Slide 33 text

Slide 34

Slide 34 text

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

Slide 35

Slide 35 text

struct ContentView: View { var body: some View { return VStack { return ViewBuilder.buildBlock( Text(item.title), Text(item.subtitle) .foregroundColor(Color.gray) } } } } ͜͏ղऍ͞ΕΔ

Slide 36

Slide 36 text

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) } } } }

Slide 37

Slide 37 text

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) } } } }

Slide 38

Slide 38 text

@_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

Slide 39

Slide 39 text

Slide 40

Slide 40 text

Opaque Result Type

Slide 41

Slide 41 text

• δΣωϦΫεͷΑ͏ͳ΋ͷ • some Protocol ͷΑ͏ͳܕ͕ Opaque Result Type • some View ͸  ʮ۩ମతͳܕ͸ެ։͠ͳ͍͚ͲɺViewϓϩτίϧʹద߹ͨ͠ԿΒ͔ͷܕʯ  Ͱ͋Δ͜ͱΛද͢ SE-0244: Opaque Result Type

Slide 42

Slide 42 text

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෣͏

Slide 43

Slide 43 text

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

Slide 44

Slide 44 text

struct ContentView: View { var body: VStack> { return VStack ( return ViewBuilder.buildBlock( Text(item.title), Text(item.subtitle) .foregroundColor(Color.gray) ) } } } ۩ମܕΛࢦఆͯ͠΋0, ͜ͷܗͳΒɺ΋͸΍4XJGUະຬͷจ๏Ͱ΋ҙຯ͕௨Δ

Slide 45

Slide 45 text

ϝϦοτ • ͖ͬ͢Γ͢Δ SE-0244: Opaque Result Type

Slide 46

Slide 46 text

ϝϦοτ • ͖ͬ͢Γ͢Δ SE-0244: Opaque Result Type VStack> ͦΕ͚ͩͰ͸ͳ͍ ʢ˞Computed property ͸ܕએݴΛলུͰ͖ͳ͍ʣ

Slide 47

Slide 47 text

• ίϯύΠϧ࣌ʹԿΒ͔ͷܕͰ͋Δ͜ͱ͕֬ఆ͢Δ • ίϯύΠϧ࣌ʹ෼͔ΔͷͰɺ࣮ߦ࣌ʹύϑΥʔϚϯεϩε͕ͳ͍ SE-0244: Opaque Result Type

Slide 48

Slide 48 text

SE-0244: Opaque Result Type func map(l: List , _ f: A -> B) -> List { 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

Slide 49

Slide 49 text

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

Slide 50

Slide 50 text

struct ContentView: View { var body: AnyView { AnyView(VStack { Text(item.title) Text(item.subtitle) .foregroundColor(Color.gray) }) } } ܕফڈ͸Ͱ͖Δ͕ɺ ύϑΥʔϚϯεϩε͕͋Δ

Slide 51

Slide 51 text

Slide 52

Slide 52 text

·ͱΊ

Slide 53

Slide 53 text

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

Slide 54

Slide 54 text

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

Slide 55

Slide 55 text

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

Slide 56

Slide 56 text

No content

Slide 57

Slide 57 text

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

Slide 58

Slide 58 text

• Swift Evolution • https://github.com/apple/swift-evolution/blob/master/proposals/0255-omit-return.md • https://github.com/apple/swift-evolution/blob/9992cf3c11c2d5e0ea20bee98657d93902d5b174/proposals/XXXX- function-builders.md • https://github.com/apple/swift-evolution/blob/master/proposals/0244-opaque-result-types.md References

Slide 59

Slide 59 text

• 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

Slide 60

Slide 60 text

Enjoy SwiftUI!