A story about me trying to make a router that manages when, how and which view to transit in a SwiftUI app

Transcript

1. 4XJGU6*
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2. } var employedBy = "YUMEMI Inc." var job = "iOS Tech Lead" var favoriteLanguage = "Swift" var twitter = "@lovee" var qiita = "lovee" var github = "el-hoshino" var additionalInfo = """ ϒϩάॻ͘·Ͱ͕ iOSDC ͩΑʁ """ final class Me: Developable, Talkable {
3. Ұൠతͳ
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   ͷը໘ભҠ
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   ભҠʣ struct ParentView: View { @State var showsChild = false var body: some View { Text("Parent") .fullScreenCover(isPresented: $showsChild, content: { ChildView() }) } } ભҠ੍ޚ༻ 
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4. Ұൠతͳ
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   ͷը໘ભҠ
   ʢ1VTI
   ભҠʣ struct ParentView: View { @State var showsChild = false var body: some View { NavigationLink(destination: { ChildView() }, label: { Text("Show Child") }) } } ભҠઌ ભҠϑϥάʜʁ
5. Ұൠతͳ
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   ͷը໘ભҠ
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   ભҠʣ struct ParentView: View { @State var showsChild = false var body: some View { NavigationLink(isActive: $showsChild, destination: { ChildView() }, label: { EmptyView() }) } } ભҠઌ ભҠϑϥά ભҠ੍ޚ͕ 
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6. Ұൠతͳ
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   ભҠʣ struct ParentView: View { @State var showsChild = false var body: some View { Text("Parent") .background(NavigationLink( isActive: $showsChild, destination: { ChildView() }, label: { EmptyView() } )) } } ભҠઌ ભҠϑϥά ભҠ੍ޚ༻ 
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7. 4XJGU6*
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8. 3PVUFS
   Λ࡞Δ final class Router: ObservableObject { @Published var showsChild = false func navigationBinding() -> Binding<Bool> { return .init(get: { [unowned self] in return self.showsChild }, set: { [unowned self] in self.showsChild = $0 }) } @ViewBuilder func nextView() -> some View { ChildView() } } ભҠઌ ભҠϑϥά
9. 3PVUFS
   Λ࢖͏ struct ParentView: View { @StateObject var router = Router() var body: some View { Text("Parent") .background(NavigationLink( isActive: router.navigationBinding(), destination: { router.nextView() }, label: { EmptyView() } )) } }
10. ͝੩ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠ ͳ༁͋Δ͔ʂ
11. 3PVUFS
    Λ࢖͏ struct ParentView: View { @StateObject var router = Router() var body: some View { Text("Parent") .background(NavigationLink( isActive: router.navigationBinding(), destination: { router.nextView() }, label: { EmptyView() } )) } } 7JFX
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12. ݱঢ়ͷ໰୊఺ w Ͱ͖Ε͹
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13. ཧ૝ protocol ParentRouterDelegate: ObservableObject { func parentDidSubmit() } struct ParentView<R: ParentRouterDelegate>: View { @ObservedObject var router: R var body: some View { Button { router.parentDidSubmit() } label: { Text("Submit") } } } ໘౗ͳ࡞ۀ͸্ҐϨΠϠʔͷ͸ͣͷ 
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14. Ξϓϩʔν w 3PVUFS
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15. 7JFX
    ͔Β΍Γ͍ͨભҠ protocol ParentRouterDelegate: ObservableObject { func parentDidSubmit() } struct ParentView<R: ParentRouterDelegate>: View { @ObservedObject var router: R // ... }
16. ભҠΛ࣮ݱ͢ΔͨΊͷ࢓૊Έ enum ViewID { //... } protocol RouterObject: ObservableObject { associatedtype NextView: View func pushFlag(for view: ViewID) -> Binding<Bool> func modalFlag(for view: ViewID) -> Binding<Bool> func nextView(after view: ViewID) -> NextView } struct RoutingModifier<R: RouterObject>: ViewModifier { @ObservedObject var router: R var viewID: ViewID func body(content: Content) -> some View { content .background(//... .fullScreenCover(//... } } extension View { func injectRouter<R: RouterObject>(_ router: R, as viewID: ViewID) -> some View { modifier(RoutingModifier(router: router, viewID: viewID)) } } ͜ΕͰݺͼग़͠ݩ͕ 
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17. 3PVUFS
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18. 3PVUFS
    ͷॳظ࣮૷ final class Router: ObservableObject { @Published var parentViewRoute: ViewID? // ... func makeParentView() -> some View { ParentView(router: self) .injectRouter(self, as: .parent) } func makeChildView() -> some View { ChildView() } } 3PVUFS
    ͕ඞཁʹԠͯ͡ 
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19. 3PVUFS
    ͷભҠ
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    ద߹ extension TestRouter: ParentRouterDelegate { func parentDidSubmit() { parentViewRoute = .child } } ભҠ͕ඞཁͳͱ͖ͷಈ࡞͚ͩΛ 
 ઐ೦Ͱ͖Δ
20. 3PVUFS
    ͷભҠ࢓૊Έͷద߹ extension TestRouter: TestRouterObject { func pushFlag(for view: ViewID) -> Binding<Bool> { switch view { case .parent: return .init(get: { [unowned self] in self.parentViewRoute != nil }, set: { [unowned self] in assert($0 == false); self.parentViewRoute = nil }) case .child: return .constant(false) } } func modalFlag(for view: ViewID) -> Binding<Bool> { return .constant(false) } @ViewBuilder func nextView(after view: ViewID) -> some View { switch view { case .parent: if let route = parentViewRoute, route == .child { makeChildView() } case .child: EmptyView() } } } 4XJGU6*
    ͷ࢓্༷ɺ 
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21. ׬੒͸͕ͨ͠ 
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22. %&.0
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