wip

0213-navigation-stacks-pt3/README.md

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+## [Point-Free](https://www.pointfree.co)
+
+> #### This directory contains code from Point-Free Episode: [SwiftUI Navigation: Stacks](https://www.pointfree.co/episodes/ep213-swiftui-navigation-stacks)
+>
+> When all-new SwiftUI navigation tools were announced at WWDC, the one that got the most attention by far was NavigationStack, which powers navigation with an array. It is extremely powerful, but comes with trade-offs and new complexities.

0213-navigation-stacks-pt3/StackExploration/StackExploration.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>

0213-navigation-stacks-pt3/StackExploration/StackExploration/Assets.xcassets/AccentColor.colorset/Contents.json

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+{
+  "colors" : [
+    {
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

0213-navigation-stacks-pt3/StackExploration/StackExploration/Assets.xcassets/AppIcon.appiconset/Contents.json

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+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

0213-navigation-stacks-pt3/StackExploration/StackExploration/Assets.xcassets/Contents.json

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+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

0213-navigation-stacks-pt3/StackExploration/StackExploration/ContentView.swift

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+import SwiftUI
+
+//struct CounterDestination: Hashable {
+//  var initialCount = 0
+//  var fact: FactSheetState?
+//}
+
+class AppModel: ObservableObject {
+  @Published var path: [Destination] {
+    didSet {
+      self.bind()
+    }
+  }
+
+  init(path: [Destination] = []) {
+    self.path = path
+    self.bind()
+  }
+
+  enum Destination: Hashable {
+    case counter(CounterModel)
+    case letter(String)
+  }
+
+  func bind() {
+    for destination in self.path {
+      switch destination {
+      case let .counter(model):
+        model.onTapLetter = { [weak self] letter in
+          guard let self else { return }
+          self.path.append(.letter(letter))
+        }
+        model.onTapNumber = { [weak self] number in
+          guard let self else { return }
+          self.path.append(.counter(CounterModel(count: number)))
+        }
+
+      case .letter:
+        break
+      }
+    }
+  }
+}
+
+struct ContentView: View {
+  @ObservedObject var model: AppModel
+//  {
+//    var path = NavigationPath()
+//    path.append("A")
+//    path.append("B")
+//    path.append("C")
+//    path.append(CounterModel(count: 42))
+//    path.append(
+//      CounterModel(
+//        count: 1_000,
+//        fact: FactSheetState(message: "1,000 is the number of words a picture is worth.")
+//      )
+//    )
+//    return path
+//  }()
+
+  var body: some View {
+    VStack {
+      Button {
+        self.randomStackButtonTapped()
+      } label: {
+        Text("Random stack")
+      }
+      Button {
+        var count = 0
+        for destination in self.model.path {
+          guard case let .counter(counter) = destination
+          else { continue }
+          count += counter.count
+        }
+        print("Sum", count)
+      } label: {
+        Text("Sum the counts")
+      }
+      NavigationStack(path: self.$model.path) {
+        ListView()
+          .navigationDestination(for: AppModel.Destination.self) { destination in
+            switch destination {
+            case let .counter(model):
+              CounterView(model: model)
+            case let .letter(letter):
+              ListView()
+                .navigationTitle(Text(letter))
+            }
+          }
+//          .navigationDestination(for: String.self) { letter in
+//            ListView()
+//              .navigationTitle(Text(letter))
+//          }
+//          .navigationDestination(for: CounterModel.self) { model in
+//            CounterView(model: model)
+////            ListView()
+////              .navigationTitle(Text("\(number)"))
+//          }
+          .navigationTitle("Root")
+      }
+      .onChange(of: self.model.path) { path in
+        dump(path)
+      }
+    }
+  }
+
+  func randomStackButtonTapped() {
+    self.model.path = []
+    for _ in 0...Int.random(in: 3...6) {
+      if Bool.random() {
+        self.model.path.append(.counter(CounterModel(count: Int.random(in: 1...1_000))))
+      } else {
+        self.model.path.append(
+          .letter(
+            String(
+              Character(
+                UnicodeScalar(
+                  UInt32.random(
+                    in: "A".unicodeScalars.first!.value..."Z".unicodeScalars.first!.value
+                  )
+                )!
+              )
+            )
+          )
+        )
+      }
+    }
+  }
+}
+
+class CounterModel: ObservableObject, Hashable {
+  @Published var count = 0
+  @Published var fact: FactSheetState?
+
+  var onTapNumber: (Int) -> Void = { _ in }
+  var onTapLetter: (String) -> Void = { _ in }
+
+  init(
+    count: Int = 0,
+    fact: FactSheetState? = nil
+  ) {
+    self.count = count
+    self.fact = fact
+  }
+
+  func numberButtonTapped(number: Int) {
+    self.onTapNumber(number)
+  }
+
+  func letterButtonTapped(letter: String) {
+    self.onTapLetter(letter)
+  }
+
+  func decrementButtonTapped() {
+    self.count -= 1
+  }
+  func incrementButtonTapped() {
+    self.count += 1
+  }
+  func factButtonTapped() {
+    Task { @MainActor in
+      let (data, _) = try await URLSession.shared
+        .data(from: URL(string: "http://numbersapi.com/\(self.count)")!)
+      self.fact = FactSheetState(
+        message: String(decoding: data, as: UTF8.self)
+      )
+    }
+  }
+
+  static func == (lhs: CounterModel, rhs: CounterModel) -> Bool {
+    lhs === rhs
+  }
+
+  func hash(into hasher: inout Hasher) {
+    hasher.combine(ObjectIdentifier(self))
+  }
+}
+
+struct CounterView: View {
+  @ObservedObject var model: CounterModel
+//  @StateObject var model = CounterModel()
+
+  var body: some View {
+    List {
+      HStack {
+        Button("-") { self.model.decrementButtonTapped() }
+        Text("\(self.model.count)")
+        Button("+") { self.model.incrementButtonTapped() }
+      }
+      .buttonStyle(.borderless)
+
+      Button {
+        self.model.factButtonTapped()
+      } label: {
+        Text("Number fact")
+      }
+      .buttonStyle(.borderless)
+
+      Section {
+        Button {
+          self.model.letterButtonTapped(letter: "A")
+        } label: {
+          Text("Go to screen A")
+        }
+        Button {
+          self.model.letterButtonTapped(letter: "B")
+        } label: {
+          Text("Go to screen B")
+        }
+        Button {
+          self.model.letterButtonTapped(letter: "C")
+        } label: {
+          Text("Go to screen C")
+        }
+        Button {
+          self.model.numberButtonTapped(number: self.model.count)
+        } label: {
+          Text("Go to screen \(self.model.count)")
+        }
+//        .buttonStyle(.navigationLink)
+
+//        NavigationLink(value: ContentView.Destination.letter("A")) {
+//          Text("Go to screen A")
+//        }
+//        NavigationLink(value: ContentView.Destination.letter("B")) {
+//          Text("Go to screen B")
+//        }
+//        NavigationLink(value: ContentView.Destination.letter("C")) {
+//          Text("Go to screen C")
+//        }
+//        NavigationLink(value: ContentView.Destination.counter(CounterModel(count: self.model.count))) {
+//          Text("Go to screen \(self.model.count)")
+//        }
+      }
+    }
+    .sheet(item: self.$model.fact) { fact in
+      Text(fact.message)
+    }
+    .navigationTitle(Text("\(self.model.count)"))
+  }
+}
+struct FactSheetState: Identifiable, Hashable {
+  var message = ""
+  var id: Self { self }
+}
+
+struct ContentView_Previews: PreviewProvider {
+  static var previews: some View {
+    ContentView(model: AppModel())
+  }
+}
+
+struct ListView: View {
+  var body: some View {
+    List {
+      NavigationLink(value: AppModel.Destination.letter("A")) {
+        Text("Go to screen A")
+      }
+      NavigationLink(value: AppModel.Destination.letter("B")) {
+        Text("Go to screen B")
+      }
+      NavigationLink(value: AppModel.Destination.letter("C")) {
+        Text("Go to screen C")
+      }
+      NavigationLink(value: AppModel.Destination.counter(CounterModel(count: 42))) {
+        Text("Go to screen 42")
+      }
+    }
+  }
+}

0213-navigation-stacks-pt3/StackExploration/StackExploration/Info.plist

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>NSAppTransportSecurity</key>
+	<dict>
+		<key>NSAllowsArbitraryLoads</key>
+		<true/>
+	</dict>
+</dict>
+</plist>

0213-navigation-stacks-pt3/StackExploration/StackExploration/Preview Content/Preview Assets.xcassets/Contents.json

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+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

0213-navigation-stacks-pt3/StackExploration/StackExploration/StackExplorationApp.swift

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+import SwiftUI
+
+@main
+struct StackExplorationApp: App {
+  var body: some Scene {
+    WindowGroup {
+      ContentView(
+        model: AppModel(
+          path: [
+            .counter(CounterModel())
+          ]
+        )
+      )
+    }
+  }
+}