ゼロから始めるPreferenceの実装 / Let's implement Preferences from scratch

Transcript

3. ી ી
4. var employedBy = "YUMEMI Inc." var job = "iOS Developer" var organizerOf = "HAKATA.swift" var favoriteLanguage = "Swift" var twitter = "@lovee" var qiita = "lovee" var github = "el-hoshino" var additionalInfo = """ ͜Ε͔Β@Environment(\.keyPath)એڭࢣͱ ໊৐͍͖͍ͬͯͨͱࢥ͍·͢! """ final class Me: Developable, Talkable { }
5. ࠓ೔΋@Environment(\.keyPath)ͷ࿩Λ͠·͢
6. ࠓ೔΋@Environment(\.keyPath)ͷ࿩Λ͠·͢ ͱݟ͔͚ͤͯʜ
7. ࠓ೔΋@Environment(\.keyPath)ͷ࿩Λ͠·͢ ͱݟ͔͚ͤͯʜ ͦͷٯͷύλʔϯͷ࿩Λ͠·͢ʂ
8. ʮٯʯ
   ͱ͸ var body: some View { VStack { Text("Title") LazyVStack { ForEach(items) { item in Text(item.title) } } } } " " &OWJSPONFOU 1SFGFSFODF
9. θϩ͔Β࢝ΊΔ1SFGFSFODFͷ࣮૷ for
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   GFBU
   +BQBOa SFHJPO TXJGU
   
10. εςοϓ PreferenceKeyʹద߹ͨ͠structΛ࡞Δ struct IsProcessingKey: PreferenceKey { // ͜ͷPreferenceʹஔ͍ͯͷσϑΥϧτ஋ static var defaultValue: Bool = false static func reduce(value: inout Bool, nextValue: () -> Bool) { // ෳ਺ͷࢠڙ͔ΒPreferenceใࠂ͞Εͨ࣌ͷղܾ๏ } }
11. εςοϓ ঢ়ଶΛใࠂ͍ͨ͠ࢠϏϡʔͰ.preferenceΛݺͿ struct ChildView: View { @State private var isProcessing: Bool = false var body: some View { SomeComponent() .preference(key: IsProcessingKey.self, value: isProcessing) } }
12. εςοϓ ঢ়ଶΛड͚औΓ͍ͨ਌ϏϡʔͰ.onPreferenceChangeΛݺͿ struct ParentView: View { var body: some View { ChildView() .onPreferenceChange(IsProcessingKey.self) { isProcessing in // isProcessingͷ஋͕มΘͬͨ࣌ͷॲཧ } } }
13. Demo
14. ؾΛ෇͚ΔϙΠϯτ w ঢ়ଶใࠂΛड͚Δ਌Ϗϡʔͷ
    .onPreferenceChange
    ͷݺͼग़͢͠Δ৔ॴʹ͸ ஫ҙΛ
    w ForEach
    ΍
    Group
    ͷΑ͏ͳෳ਺ͷ
    3FTPMWFE7JFX
    Λ࡞Δ͔΋͠Εͳ͍
    View
    ʹ͚ͭΔͷ͸ආ͚Δ΂͠
    w .reduce
    ͷ࣮૷ΛͪΌΜͱߟ͑Δ΂͠
    w Α͋͘Δ࣮૷ύλʔϯ
    w ϑϥάͷ৔߹͸࿦ཧ࿨ʗ࿦ཧੵ͕ཉ͍͠ͳͲ
    w ਺஋ͷ৔߹͸શ਺஋ͷ࿨΍ੵɺ΋͘͠͸࠷େ஋΍࠷খ஋ͳͲ
    w ܕʹΑΒͣ࠷ॳͷσʔλ͕ཉ͍͠ʗ࠷ޙͷσʔλ͕ཉ͍͠ͳͲ
15. Demo
16. 5JQT w 7JFXΛ֦ுͯ͠ɺ1SFGFSFODF,FZͷܕΛ௚઀࢖Θͣʹ࢖͑ΔΑ͏ʹϝιου࡞ͬ ͓ͯ͘ͱศར
    w ঢ়ଶΛใࠂ͢Δϝιου
    • func property(_ value: Property) -> some View w ঢ়ଶΛड͚औΔϝιου
    • func onPropertyChange(_ action: @escaping (Property) -> Void) -> some View w ঢ়ଶΛड͚औͬͯͦͷ··ผͷঢ়ଶʹΞαΠϯ͢Δϝιου
    • func bindingProperty(to state: Binding<Property>) -> some View
17. ࢀߟࢿྉ IUUQTEFWFMPQFSBQQMFDPNEPDVNFOUBUJPOTXJGUVJQSFGFSFODFT