[WIP] WorkflowSwiftUI without ObservedObject

Samples/SwiftUITestbed/Sources/MainScreen.swift

@@ -18,8 +18,9 @@ import MarketUI
 import MarketWorkflowUI
 import ViewEnvironment
 import WorkflowSwiftUIExperimental
+import WorkflowUI
 
-struct MainScreen: SwiftUIScreen {
+struct MainScreen: View, Screen {
     let title: String
     let didChangeTitle: (String) -> Void
 
@@ -32,14 +33,6 @@ struct MainScreen: SwiftUIScreen {
 
     let didTapClose: (() -> Void)?
 
-    static func makeView(model: ObservableValue<MainScreen>) -> some View {
-        MainScreenView(model: model)
-    }
-}
-
-private struct MainScreenView: View {
-    @ObservedObject var model: ObservableValue<MainScreen>
-
     @Environment(\.viewEnvironment.marketStylesheet) private var styles: MarketStylesheet
     @Environment(\.viewEnvironment.marketContext) private var context: MarketContext
 
@@ -56,9 +49,9 @@ private struct MainScreenView: View {
 
             TextField(
                 "Text",
-                text: model.binding(
-                    get: \.title,
-                    set: \.didChangeTitle
+                text: Binding(
+                    get: { title },
+                    set: didChangeTitle
                 )
             )
             .focused($focusedField, equals: .title)
@@ -67,10 +60,10 @@ private struct MainScreenView: View {
             ToggleRow(
                 style: context.stylesheets.testbed.toggleRow,
                 label: "All Caps",
-                isEnabled: model.allCapsToggleIsEnabled,
-                isOn: model.binding(
-                    get: \.allCapsToggleIsOn,
-                    set: \.didChangeAllCapsToggle
+                isEnabled: allCapsToggleIsEnabled,
+                isOn: Binding(
+                    get: { allCapsToggleIsOn },
+                    set: didChangeAllCapsToggle
                 )
             )
 
@@ -81,12 +74,12 @@ private struct MainScreenView: View {
 
             Button(
                 "Push Screen",
-                action: model.didTapPushScreen
+                action: didTapPushScreen
             )
 
             Button(
                 "Present Screen",
-                action: model.didTapPresentScreen
+                action: didTapPresentScreen
             )
 
             Button(

WorkflowSwiftUIExperimental/Sources/Screen+View.swift

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2023 Square Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#if canImport(UIKit)
+
+import SwiftUI
+import Workflow
+import WorkflowUI
+
+public extension Screen where Self: View {
+    func viewControllerDescription(environment: ViewEnvironment) -> ViewControllerDescription {
+        return ViewControllerDescription(
+            type: UIHostingController<RootView<Self>>.self,
+            environment: environment,
+            build: {
+                UIHostingController(
+                    rootView: RootView(
+                        model: RootViewModel(
+                            content: self,
+                            environment: environment
+                        )
+                    )
+                )
+            },
+            update: { hostingController in
+                let object = hostingController.rootView.model
+                object.content = self
+                object.environment = environment
+            }
+        )
+    }
+}
+
+private final class RootViewModel<Content: View>: ObservableObject {
+    @Published var content: Content
+    @Published var environment: ViewEnvironment
+
+    init(content: Content, environment: ViewEnvironment) {
+        self.content = content
+        self.environment = environment
+    }
+}
+
+private struct RootView<Content: View>: View {
+    @ObservedObject var model: RootViewModel<Content>
+
+    var body: some View {
+        model.content
+            .environment(\.viewEnvironment, model.environment)
+    }
+}
+
+#endif