State

import SwiftUI
class TapCountObservable: ObservableObject {
 @Published var tapCount = 0
}
struct TapCountStruct : Identifiable {
 var id = 0
 var tapCount = 0
}
class TapCountRepository: ObservableObject {
 @Published var items: [TapCountStruct] = []
 func add() {
 items.append(TapCountStruct(id: items.count))
 }
 func increment() {
 if !items.isEmpty {
 items[items.count - 1].tapCount += 1
 }
 }
}
struct StatePlayground: View {
 @State var tapCount = 0
 @State var hasStateTapped: Bool? // Test optional vars
 @StateObject var tapCountObservable: TapCountObservable
 @State var tapCountStruct: TapCountStruct
 @StateObject var tapCountRepository = TapCountRepository() // Test ForEach observable
 init() {
 // Test that we can initialze state property wrappers
 _tapCountObservable = StateObject(wrappedValue: TapCountObservable())
 _tapCountStruct = State(wrappedValue: TapCountStruct())
 }
 var body: some View {
 List {
 Section {
 NavigationLink("Push another", value: PlaygroundType.state)
 NavigationLink("Push binding view") {
 StatePlaygroundDestinationBindingView(tapCount: $tapCount)
 }
 }
 Section {
 if hasStateTapped == true {
 Text("State tap count: \(tapCount)")
 } else {
 Text("Tap below to increment state tap count")
 }
 Button("State") {
 tapCount += 1
 hasStateTapped = true
 }
 StatePlaygroundBindingView(tapCount: $tapCount)
 }
 Section {
 Text("Observable tap count: \(tapCountObservable.tapCount)")
 Button("Observable") {
 tapCountObservable.tapCount += 1
 }
 StatePlaygroundBindingView(tapCount: $tapCountObservable.tapCount)
 }
 Section {
 Text("Struct tap count: \(tapCountStruct.tapCount)")
 Button("Struct") {
 tapCountStruct.tapCount += 1
 }
 StatePlaygroundStructBindingView(tapCountStruct: $tapCountStruct)
 }
 Section {
 Text("Struct tap count (field): \(tapCountStruct.tapCount)")
 Button("Struct (field)") {
 tapCountStruct.tapCount += 1
 }
 StatePlaygroundBindingView(tapCount: $tapCountStruct.tapCount)
 }
 Section {
 ForEach(tapCountRepository.items) { item in
 Text("Repository item tap count: \(item.tapCount)")
 }
 Button("Add item") { tapCountRepository.add() }
 Button("Increment last") { tapCountRepository.increment() }
 }
 }
 .onChange(of: tapCount) {
 logger.log("onChange(of: tapCount): \(0ドル)")
 }
 .onChange(of: tapCountObservable.tapCount) {
 logger.log("onChange(of: tapCountObservable.tapCount): \(0ドル)")
 }
 .onChange(of: tapCountStruct.tapCount) {
 logger.log("onChange(of: tapCountStruct.tapCount): \(0ドル)")
 }
 .toolbar {
 PlaygroundSourceLink(file: "StatePlayground.swift")
 }
 }
}
struct StatePlaygroundBindingView: View {
 @Binding var tapCount: Int
 var body: some View {
 Button("Binding") {
 tapCount += 1
 }
 }
}
struct StatePlaygroundStructBindingView: View {
 @Binding var tapCountStruct: TapCountStruct
 var body: some View {
 Button("Binding") {
 tapCountStruct.tapCount += 1
 }
 }
}
struct StatePlaygroundDestinationBindingView: View {
 @Binding var tapCount: Int
 var body: some View {
 VStack {
 SubView1(tapCount: _tapCount)
 SubView2(tapCount: _tapCount)
 }
 .navigationTitle("Binding View")
 }
 struct SubView1: View {
 @Binding var tapCount: Int
 var body: some View {
 Button("Bound tap count 1: \(tapCount)") {
 tapCount += 1
 }
 .buttonStyle(.bordered)
 }
 }
 struct SubView2: View {
 @Binding var tapCount: Int
 var body: some View {
 Button("Bound tap count 2: \(tapCount)") {
 tapCount += 1
 }
 .buttonStyle(.bordered)
 }
 }
}