SwiftUI で複数のアラート表示を管理する

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1. :VUBLB
   5BKJLB 4XJGU6*
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3. 4XJGU6*
   ͰͷΞϥʔτදࣔ
   ͭͷ৔߹  struct ContentView: View { @State var isPresented = false var body: some View { Button("Alert") { isPresented = true } .alert("Alert", isPresented: $isPresented) { Button("Close", role: .cancel) {} } } }
4. 4XJGU6*
   ͰͷΞϥʔτදࣔ
   ͭͷ৔߹  struct ContentView: View { @State var isPresented = false var body: some View { Button("Alert") { isPresented = true } .alert("Alert", isPresented: $isPresented) { Button("Close", role: .cancel) {} } } } !4UBUF
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   #PPM
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5. 4XJGU6*
   ͰͷΞϥʔτදࣔ
   ͭͷ৔߹  struct ContentView: View { @State var isPresented = false var body: some View { Button("Alert") { isPresented = true } .alert("Alert", isPresented: $isPresented) { Button("Close", role: .cancel) {} } } } #JOEJOH#PPM
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   JT1SFTFOUFE
   Λ౉͢
6. 4XJGU6*
   ͰͷΞϥʔτදࣔ
   ͭͷ৔߹  struct ContentView: View { @State var isPresented1 = false @State var isPresented2 = false var body: some View { VStack { Button("Alert 1") { isPresented1 = true } Button("Alert 2") { isPresented2 = true } } .alert("Alert 1", isPresented: $isPresented1) { Button("Close", role: .cancel) {} } .alert("Alert 2", isPresented: $isPresented2) { Button("Close", role: .cancel) {} } } }
7. 4XJGU6*
   ͰͷΞϥʔτදࣔ
   ͭͷ৔߹  struct ContentView: View { @State var isPresented1 = false @State var isPresented2 = false var body: some View { VStack { Button("Alert 1") { isPresented1 = true } Button("Alert 2") { isPresented2 = true } } .alert("Alert 1", isPresented: $isPresented1) { Button("Close", role: .cancel) {} } .alert("Alert 2", isPresented: $isPresented2) { Button("Close", role: .cancel) {} } } } ͦΕͧΕͷΞϥʔτʹରԠ͢Δ
   ද੍ࣔޚϑϥάΛ࣋ͭ
8. 🎉 
9. ຊ౰ʹͪΌΜͱ
   Ξϥʔτͷදࣔඇදࣔঢ়ଶΛ
   දݱͰ͖ͯΔɻɻʁ 
10. 4XJGU6*
    ͰͷΞϥʔτදࣔ
    ͭͷ৔߹  struct ContentView: View { @State var isPresented1 = false @State var isPresented2 = false var body: some View { VStack { Button("Alert 1") { isPresented1 = true } Button("Alert 2") { isPresented2 = true } } .alert("Alert 1", isPresented: $isPresented1) { Button("Close", role: .cancel) {} } .alert("Alert 2", isPresented: $isPresented2) { Button("Close", role: .cancel) {} } } } isPresented1 isPresented2 false false ͲͪΒ΋ඇදࣔ true false "MFSU
    
    ͕දࣔ false true "MFSU
    
    ͕දࣔ true true "MFSU
    
    ͱ
    "MFSU
    
    ͕දࣔ ʢʁʁʁʣ
11. 4XJGU6*
    ͰͷΞϥʔτදࣔ
    ͭͷ৔߹  struct ContentView: View { @State var isPresented1 = false @State var isPresented2 = false var body: some View { VStack { Button("Alert 1") { isPresented1 = true } Button("Alert 2") { isPresented2 = true } } .alert("Alert 1", isPresented: $isPresented1) { Button("Close", role: .cancel) {} } .alert("Alert 2", isPresented: $isPresented2) { Button("Close", role: .cancel) {} } } } isPresented1 isPresented2 false false ͲͪΒ΋ඇදࣔ true false "MFSU
    
    ͕දࣔ false true "MFSU
    
    ͕දࣔ true true "MFSU
    
    ͱ
    "MFSU
    
    ͕දࣔ ʢʁʁʁʣ ࣮ࡍʹೋͭͷΞϥʔτ͕ಉ࣌ʹ දࣔ͞ΕΔ͜ͱ͸ͳ͍ɻ
    ͕ɺೋͭͷΞϥʔτ͕දࣔ͞Εͯ ͍ΔΑ͏ͳදݱʹݟ͑Δɻ
12. վળͯ͠ΈΔ 
13. 4XJGU6*
    Ͱͷෳ਺Ξϥʔτදࣔ  struct ContentView: View { @State var alert: MyAlert? var body: some View { VStack { Button("Alert 1") { alert = .alert1 } Button("Alert 2") { alert = .alert2 } } .alert("Alert 1", isPresented: Binding( get: { alert == .alert1 }, set: { if !$0 { alert = nil } } )) { Button("Close", role: .cancel) { alert = nil } } .alert("Alert 2", isPresented: Binding( get: { alert == .alert2 }, set: { if !$0 { alert = nil } } )) { Button("Close", role: .cancel) { alert = nil } } } } enum MyAlert: Equatable { case alert1, alert2 } &OVN
    Λར༻ͯ͠
    ΞϥʔτͷछྨΛఆٛ
14. 4XJGU6*
    Ͱͷෳ਺Ξϥʔτදࣔ  struct ContentView: View { @State var alert: MyAlert? var body: some View { VStack { Button("Alert 1") { alert = .alert1 } Button("Alert 2") { alert = .alert2 } } .alert("Alert 1", isPresented: Binding( get: { alert == .alert1 }, set: { if !$0 { alert = nil } } )) { Button("Close", role: .cancel) { alert = nil } } .alert("Alert 2", isPresented: Binding( get: { alert == .alert2 }, set: { if !$0 { alert = nil } } )) { Button("Close", role: .cancel) { alert = nil } } } } enum MyAlert: Equatable { case alert1, alert2 }
15. 4XJGU6*
    Ͱͷෳ਺Ξϥʔτදࣔ  struct ContentView: View { @State var alert: MyAlert? var body: some View { VStack { Button("Alert 1") { alert = .alert1 } Button("Alert 2") { alert = .alert2 } } .alert("Alert 1", isPresented: Binding( get: { alert == .alert1 }, set: { if !$0 { alert = nil } } )) { Button("Close", role: .cancel) { alert = nil } } .alert("Alert 2", isPresented: Binding( get: { alert == .alert2 }, set: { if !$0 { alert = nil } } )) { Button("Close", role: .cancel) { alert = nil } } } } enum MyAlert: Equatable { case alert1, alert2 } Ξϥʔτͷදࣔঢ়ଶΛ 0QUJPOBM
    Λ࢖ͬͯදݱ alert .none ͲͪΒ΋ඇදࣔ .some(.alert1) "MFSU
    
    ͕දࣔ .some(.alert2) "MFSU
    
    ͕දࣔ
16. 4XJGU6*
    Ͱͷෳ਺Ξϥʔτදࣔ  struct ContentView: View { @State var alert: MyAlert? var body: some View { VStack { Button("Alert 1") { alert = .alert1 } Button("Alert 2") { alert = .alert2 } } .alert("Alert 1", isPresented: Binding( get: { alert == .alert1 }, set: { if !$0 { alert = nil } } )) { Button("Close", role: .cancel) { alert = nil } } .alert("Alert 2", isPresented: Binding( get: { alert == .alert2 }, set: { if !$0 { alert = nil } } )) { Button("Close", role: .cancel) { alert = nil } } } } enum MyAlert: Equatable { case alert1, alert2 } #JOEJOH#PPM
    Λ
    ࣗલͰ࡞Δ
17. Ћ 
18. 4XJGU6*
    Ͱͷෳ਺Ξϥʔτදࣔ  struct ContentView: View { @State var alertState: AlertState<MyAlert> = .dismissed var body: some View { VStack { Button("Alert 1") { alertState = .presenting(.alert1) } Button("Alert 2") { alertState = .presenting(.alert2) } } .alert("Alert 1", isPresented: Binding( get: { alertState == .presenting(.alert1) }, set: { if !$0 { alertState = .dismissed } } )) { Button("Close", role: .cancel) { alertState = .dismissed } } .alert("Alert 2", isPresented: Binding( get: { alertState == .presenting(.alert2) }, set: { if !$0 { alertState = .dismissed } } )) { Button("Close", role: .cancel) { alertState = .dismissed } } } } enum MyAlert: Equatable { case alert1, alert2 } 0QUJPOBM
    ͷ୅ΘΓʹ
    Ξϥʔτͷදࣔঢ়ଶΛ ද͢ઐ༻ͷܕΛ༻ҙ enum AlertState<Alert> where Alert: Equatable { case dismissed case presenting(Alert) }
19. 4XJGU6*
    Ͱͷෳ਺Ξϥʔτදࣔ  struct ContentView: View { @State var alertState: AlertState<MyAlert> = .dismissed var body: some View { VStack { Button("Alert 1") { alertState = .presenting(.alert1) } Button("Alert 2") { alertState = .presenting(.alert2) } } .alert("Alert 1", isPresented: Binding( get: { alertState == .presenting(.alert1) }, set: { if !$0 { alertState = .dismissed } } )) { Button("Close", role: .cancel) { alertState = .dismissed } } .alert("Alert 2", isPresented: Binding( get: { alertState == .presenting(.alert2) }, set: { if !$0 { alertState = .dismissed } } )) { Button("Close", role: .cancel) { alertState = .dismissed } } } } enum MyAlert: Equatable { case alert1, alert2 } 0QUJPOBM
    ͷ୅ΘΓʹ
    Ξϥʔτͷදࣔঢ়ଶΛ ද͢ઐ༻ͷܕΛ༻ҙ enum AlertState<Alert> where Alert: Equatable { case dismissed case presenting(Alert) } w 0QUJPOBM
    ͷ౶ҥߏจ͕࢖͑ͳ ͍ͷͰهड़ྔ͸૿͑Δ
    w จ຺͸఻ΘΓ΍͘͢ͳͬͨ
20. ڞ௨Խͯ͠ΈΔ 
21. 4XJGU6*
    Ͱͷෳ਺Ξϥʔτදࣔͷڞ௨Խ  struct ContentView: View { @State var alertState: AlertState<MyAlert> = .dismissed var body: some View { VStack { Button("Alert 1") { alertState = .presenting(.alert1) } Button("Alert 2") { alertState = .presenting(.alert2) } } .alert("Alert 1", isPresented: Binding( get: { alertState == .presenting(.alert1) }, set: { if !$0 { alertState = .dismissed } } )) { Button("Close", role: .cancel) { alertState = .dismissed } } .alert("Alert 2", isPresented: Binding( get: { alertState == .presenting(.alert2) }, set: { if !$0 { alertState = .dismissed } } )) { Button("Close", role: .cancel) { alertState = .dismissed } } } } enum MyAlert: Equatable { case alert1, alert2 } ͜͜ͷ
    #JOEJOH
    Λຖճ ॻ͔ͳ͍ͱ͍͚ͳ͍ͷ ͸ͪΐͬͱ໘౗ enum AlertState<Alert> where Alert: Equatable { case dismissed case presenting(Alert) }
22. 4XJGU6*
    Ͱͷෳ਺Ξϥʔτදࣔͷڞ௨Խ  protocol AlertCase: Equatable {} protocol AlertStateRepresentable: Equatable { associatedtype Alert: AlertCase static var dismissed: Self { get } static func presenting(_ alert: Alert) -> Self } enum AlertState<Alert: AlertCase>: AlertStateRepresentable { case dismissed case presenting(Alert) } extension Binding where Value: AlertStateRepresentable { func isPresented(_ target: Value.Alert) -> Binding<Bool> { .init( get: { wrappedValue == .presenting(target) }, set: { if !$0 { wrappedValue = .dismissed }} ) } } ͪΐͬͱίʔυΛ௥Ճ
23. 4XJGU6*
    Ͱͷෳ਺Ξϥʔτදࣔͷڞ௨Խ  protocol AlertCase: Equatable {} protocol AlertStateRepresentable: Equatable { associatedtype Alert: AlertCase static var dismissed: Self { get } static func presenting(_ alert: Alert) -> Self } enum AlertState<Alert: AlertCase>: AlertStateRepresentable { case dismissed case presenting(Alert) } extension Binding where Value: AlertStateRepresentable { func isPresented(_ target: Value.Alert) -> Binding<Bool> { .init( get: { wrappedValue == .presenting(target) }, set: { if !$0 { wrappedValue = .dismissed }} ) } } #JOEJOH
    ʹ
    JT1SFTFOUFE
    Λੜ΍ͯ͠
    #JOEJOH#PPM
    ΁ม׵
24. 4XJGU6*
    Ͱͷෳ਺Ξϥʔτදࣔͷڞ௨Խ  struct ContentView: View { @State var alertState: AlertState<MyAlert> = .dismissed var body: some View { VStack { Button("Alert 1") { alertState = .presenting(.alert1) } Button("Alert 2") { alertState = .presenting(.alert2) } } .alert("Alert 1", isPresented: $alertState.isPresented(.alert1)) { Button("Close", role: .cancel) { alertState = .dismissed } } .alert("Alert 2", isPresented: $alertState.isPresented(.alert2)) { Button("Close", role: .cancel) { alertState = .dismissed } } } } enum MyAlert: AlertCase { case alert1, alert2 } ֤ը໘Ͱ
    #JOEJOH#PPM
    Λ࡞Βͳͯ͘ྑ͍
25. ৄ͘͠͸ϒϩά΁ w IUUQTUBKJUBKJIBUFOBCMPHDPNFOUSZ 
26. ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠
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