adds new components to the gallery

cupertino_gallery/lib/widgets/checkbox_page.dart

@@ -0,0 +1,31 @@
+import 'package:flutter/cupertino.dart';
+
+class CheckboxPage extends StatefulWidget {
+  const CheckboxPage({super.key});
+
+  @override
+  State<CheckboxPage> createState() => _CheckboxPageState();
+}
+
+class _CheckboxPageState extends State<CheckboxPage> {
+  bool _value = false;
+
+  @override
+  Widget build(BuildContext context) {
+    return CupertinoPageScaffold(
+      navigationBar: const CupertinoNavigationBar(
+        middle: Text('Checkbox'),
+      ),
+      child: Center(
+        child: CupertinoCheckbox(
+          value: _value,
+          onChanged: (bool? value) {
+            setState(() {
+              _value = value!;
+            });
+          },
+        ),
+      ),
+    );
+  }
+}