Add bindable playground

Author: colemancda

Demo/App.swiftpm/Sources/BindablePlaygrounds.swift

@@ -0,0 +1,55 @@
+#if canImport(AndroidSwiftUI)
+import AndroidSwiftUI
+#else
+import SwiftUI
+#endif
+
+import Observation
+
+@Observable
+final class ProfileModel {
+    var name = ""
+    var subscribed = false
+    var volume = 0.5
+}
+
+struct BindablePlayground: View {
+    @State private var model = ProfileModel()
+    var body: some View {
+        ScrollView {
+            BindableForm(model: model)
+        }
+    }
+}
+
+/// `@Bindable` takes the model by reference and projects `$model.property`
+/// bindings into it; writing a bound control mutates the observable, which
+/// re-evaluates the views that read it.
+struct BindableForm: View {
+    @Bindable var model: ProfileModel
+    var body: some View {
+        VStack(alignment: .leading, spacing: 0) {
+            Example("Bound TextField") {
+                VStack(alignment: .leading, spacing: 8) {
+                    TextField("Name", text: $model.name)
+                    Text(model.name.isEmpty ? "No name yet" : "Hello, \(model.name)")
+                }
+            }
+            Example("Bound Toggle") {
+                VStack(alignment: .leading, spacing: 8) {
+                    Toggle("Subscribed", isOn: $model.subscribed)
+                    Text(model.subscribed ? "Subscribed" : "Not subscribed")
+                }
+            }
+            Example("Bound Slider") {
+                VStack(alignment: .leading, spacing: 8) {
+                    Slider(value: $model.volume, in: 0...1)
+                    Text("Volume: \(Int(model.volume * 100))%")
+                }
+            }
+            Example("Shared model") {
+                Text("All three controls above bind into one @Observable model.")
+            }
+        }
+    }
+}