Add SwiftUI's View.navigate() + CaseStudy

Examples/CaseStudies/10-FullProgrammaticNavigation.swift

@@ -0,0 +1,83 @@
+import SwiftUINavigation
+
+private let readMe = """
+  This case study demonstrates how to progammaticaly navigate in SwiftUI. All your components can be isolated from navigation, just using a basic ViewModifier on your views for navigation.
+  """
+
+// ========================================================================
+// Navigation routes
+// ========================================================================
+
+enum ARoute: Equatable {
+  case b(BRoute?)
+}
+enum BRoute: Equatable {
+  case c(CRoute?)
+}
+enum CRoute: Equatable {
+  case d
+}
+
+// ========================================================================
+// Main navigation
+// ========================================================================
+
+struct FullProgrammaticNavigation: View {
+  @State var route: ARoute?
+
+  var body: some View {
+    A()
+      .onTapGesture { route = .b(.none) }
+      .navigate(when: $route, is: /ARoute.b) { _ in
+        theBView
+      }
+  }
+
+  var theBView: some View {
+    B()
+      .onTapGesture { route = .b(.c(.none)) }
+      .navigate(when: $route.case(in: /ARoute.b), is: /BRoute.c) { _ in
+        theCView
+      }
+  }
+
+  var theCView: some View {
+    C()
+      .onTapGesture { route = .b(.c(.d)) }
+      .navigate(when: $route.case(in: /ARoute.b).case(in: /BRoute.c), is: /CRoute.d) { _ in
+        theDView
+      }
+  }
+
+  var theDView: some View {
+    D()
+  }
+}
+
+// ========================================================================
+// Independent A/B/C views
+// ========================================================================
+
+struct A: View {
+  var body: some View {
+    Text("A view - Tap to navigate to B")
+  }
+}
+
+struct B: View {
+  var body: some View {
+    Text("B view - Tap to navigate to C")
+  }
+}
+
+struct C: View {
+  var body: some View {
+    Text("C view - Tap to navigate to D")
+  }
+}
+
+struct D: View {
+  var body: some View {
+    Text("D view - No navigation")
+  }
+}

Examples/CaseStudies/RootView.swift

@@ -38,6 +38,9 @@ struct RootView: View {
           NavigationLink("List of navigation links") {
             ListOfNavigationLinks(viewModel: .init())
           }
+          NavigationLink("Full programmatic navigation") {
+            FullProgrammaticNavigation()
+          }
         } header: {
           Text("Navigation links")
         }

Examples/Examples.xcodeproj/project.pbxproj

@@ -28,6 +28,7 @@
 		DCD4E685273B300F00CDF3BD /* 05-FullScreenCovers.swift in Sources */ = {isa = PBXBuildFile; fileRef = DCD4E684273B300F00CDF3BD /* 05-FullScreenCovers.swift */; };
 		DCD4E687273B30DA00CDF3BD /* 04-Popovers.swift in Sources */ = {isa = PBXBuildFile; fileRef = DCD4E686273B30DA00CDF3BD /* 04-Popovers.swift */; };
 		DCD4E68B274180F500CDF3BD /* 06-NavigationLinks.swift in Sources */ = {isa = PBXBuildFile; fileRef = DCD4E68A274180F500CDF3BD /* 06-NavigationLinks.swift */; };
+		F88630DA28488AC4004D6252 /* 10-FullProgrammaticNavigation.swift in Sources */ = {isa = PBXBuildFile; fileRef = F88630D928488AC4004D6252 /* 10-FullProgrammaticNavigation.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -53,6 +54,7 @@
 		DCD4E684273B300F00CDF3BD /* 05-FullScreenCovers.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "05-FullScreenCovers.swift"; sourceTree = "<group>"; };
 		DCD4E686273B30DA00CDF3BD /* 04-Popovers.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "04-Popovers.swift"; sourceTree = "<group>"; };
 		DCD4E68A274180F500CDF3BD /* 06-NavigationLinks.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "06-NavigationLinks.swift"; sourceTree = "<group>"; };
+		F88630D928488AC4004D6252 /* 10-FullProgrammaticNavigation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "10-FullProgrammaticNavigation.swift"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -128,6 +130,7 @@
 				CA70FED6274B1907005A0D53 /* 07-NavigationLinkList.swift */,
 				CABE9FC0272F2C0000AFC150 /* 08-Routing.swift */,
 				CA47383D272F0F9B0012CAC3 /* 09-CustomComponents.swift */,
+				F88630D928488AC4004D6252 /* 10-FullProgrammaticNavigation.swift */,
 				CA473830272F0D860012CAC3 /* CaseStudiesApp.swift */,
 				CA473831272F0D860012CAC3 /* FactClient.swift */,
 				CA47382E272F0D860012CAC3 /* RootView.swift */,
@@ -266,6 +269,7 @@
 				DCD4E687273B30DA00CDF3BD /* 04-Popovers.swift in Sources */,
 				DCD4E685273B300F00CDF3BD /* 05-FullScreenCovers.swift in Sources */,
 				CA473834272F0D860012CAC3 /* RootView.swift in Sources */,
+				F88630DA28488AC4004D6252 /* 10-FullProgrammaticNavigation.swift in Sources */,
 				CA473839272F0D860012CAC3 /* 01-Alerts.swift in Sources */,
 				DCD4E68B274180F500CDF3BD /* 06-NavigationLinks.swift in Sources */,
 				CA473838272F0D860012CAC3 /* 03-Sheets.swift in Sources */,

Sources/SwiftUINavigation/Binding.swift

@@ -61,6 +61,28 @@ extension Binding {
     )
   }
 
+  /// Creates a binding by projecting the current enum value to the value at a particular
+  /// case.
+  ///
+  /// > Note: This method is constrained to optionals so that the projected value can write `nil`
+  /// > back to the parent, which is useful for navigation, particularly dismissal.
+  ///
+  /// - Parameter casePath: A case path that identifies a particular case to unwrap.
+  /// - Returns: A binding to an enum case.
+  public func `case`<Case>(in casePath: CasePath<Value, Case?>) -> Binding<Case?> {
+    .init(
+      get: {
+        guard let value = casePath.extract(from: wrappedValue) else {
+          return .none
+        }
+        return value
+      },
+      set: { newValue in
+        wrappedValue = casePath.embed(newValue)
+      }
+    )
+  }
+
   /// Creates a binding by projecting the current optional value to a boolean describing if it's
   /// non-`nil`.
   ///

Sources/SwiftUINavigation/Navigate.swift

@@ -0,0 +1,37 @@
+extension View {
+  public func navigate<DestinationContent: View, Enum, Case>(
+    when unwrapping: Binding<Enum?>,
+    is casePath: CasePath<Enum, Case>,
+    onNavigate: ((Bool) -> Void)? = nil,
+    to destination: @escaping (Binding<Case>) -> DestinationContent
+  ) -> some View {
+    modifier(
+      NavigateViewModifier(
+        unwrapping: unwrapping,
+        casePath: casePath,
+        onNavigate: onNavigate,
+        destinationContent: destination
+      )
+    )
+  }
+}
+
+private struct NavigateViewModifier<DestinationContent: View, Enum, Case>: ViewModifier {
+  let unwrapping: Binding<Enum?>
+  let casePath: CasePath<Enum, Case>
+  let onNavigate: ((Bool) -> Void)?
+  let destinationContent: (Binding<Case>) -> DestinationContent
+
+  func body(content: Content) -> some View {
+    VStack(spacing: .zero) {
+      NavigationLink(
+        unwrapping: unwrapping,
+        case: casePath,
+        destination: destinationContent,
+        onNavigate: onNavigate ?? { _ in },
+        label: { EmptyView() }
+      )
+      content
+    }
+  }
+}