New Example - Platform Adaptive Example (#121)

* Adding Platform Adaptive Example

* Adding screenshots

using_platform_adaptive/lib/common_widgets/adaptive_button.dart

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+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+import 'package:using_platform_adaptive/platform_adaptive.dart';
+
+class AdaptiveButton extends PlatformAdaptiveWidget {
+  const AdaptiveButton(
+      {super.forcePlatform,
+      this.color,
+      required this.child,
+      this.onPressed,
+      super.key});
+
+  final void Function()? onPressed;
+  final Widget child;
+  final Color? color;
+
+  @override
+  Widget buildAndroid(BuildContext context) {
+    return MaterialButton(
+      onPressed: onPressed,
+      color: color,
+      child: child,
+    );
+  }
+
+  @override
+  Widget buildIOS(BuildContext context) {
+    return CupertinoButton(
+      onPressed: onPressed,
+      color: color,
+      child: child,
+    );
+  }
+}

using_platform_adaptive/lib/common_widgets/adaptive_date_picker.dart

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+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+import 'package:using_platform_adaptive/platform_adaptive.dart';
+
+class AdaptiveDialog extends PlatformAdaptiveWidget {
+  const AdaptiveDialog(
+      {super.key,
+      super.forcePlatform,
+      required this.title,
+      required this.actions,
+      this.content});
+
+  final String title;
+  final Widget? content;
+  final List<AdaptiveDialogAction> actions;
+
+  @override
+  Widget buildAndroid(BuildContext context) {
+    return AlertDialog(
+      title: Text(title),
+      content: content,
+      actions: actions,
+    );
+  }
+
+  @override
+  Widget buildIOS(BuildContext context) {
+    return CupertinoAlertDialog(
+      title: Text(title),
+      content: content,
+      actions: actions,
+    );
+  }
+}
+
+class AdaptiveDialogAction extends PlatformAdaptiveWidget {
+  const AdaptiveDialogAction(
+      {super.forcePlatform, this.onPressed, required this.text, super.key});
+
+  final void Function()? onPressed;
+  final String text;
+
+  @override
+  Widget buildAndroid(BuildContext context) {
+    return TextButton(onPressed: onPressed, child: Text(text));
+  }
+
+  @override
+  Widget buildIOS(BuildContext context) {
+    return CupertinoDialogAction(onPressed: onPressed, child: Text(text));
+  }
+}

using_platform_adaptive/lib/common_widgets/adaptive_indicator.dart

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+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+import 'package:using_platform_adaptive/platform_adaptive.dart';
+
+class AdaptiveIndicator extends PlatformAdaptiveWidget {
+  const AdaptiveIndicator({super.forcePlatform, super.key});
+
+  @override
+  Widget buildAndroid(BuildContext context) {
+    return const CircularProgressIndicator();
+  }
+
+  @override
+  Widget buildIOS(BuildContext context) {
+    return const CupertinoActivityIndicator();
+  }
+}

using_platform_adaptive/lib/main.dart

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+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+import 'package:using_platform_adaptive/common_widgets/adaptive_button.dart';
+import 'package:using_platform_adaptive/common_widgets/adaptive_date_picker.dart';
+import 'package:using_platform_adaptive/common_widgets/adaptive_indicator.dart';
+
+void main() {
+  runApp(const MyApp());
+}
+
+class MyApp extends StatelessWidget {
+  const MyApp({super.key});
+
+  // This widget is the root of your application.
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Platform Adaptive',
+      theme: ThemeData(
+        primarySwatch: Colors.teal,
+      ),
+      home: const MyHomePage(title: 'Using Platform Adaptive'),
+    );
+  }
+}
+
+class MyHomePage extends StatefulWidget {
+  const MyHomePage({super.key, required this.title});
+  final String title;
+
+  @override
+  State<MyHomePage> createState() => _MyHomePageState();
+}
+
+class _MyHomePageState extends State<MyHomePage> {
+  TargetPlatform? selectedPlatform;
+  final String introText = "Flutter's flagship feature is it's ability to write"
+      " code once and have it run on multiple devices. While this is great, sometimes"
+      " you want the user interface to look more native to its platform. This project"
+      " showcases the Platform Adaptive pattern, a powerful pattern that allows you"
+      " to create widgets that you write once and look natural on any device. The"
+      " demo is just set up to work on android and iOS but can be extended to work"
+      " on web, native and any other platform flutter supports.";
+
+  @override
+  Widget build(BuildContext context) {
+    final platforms = {
+      "Default": null,
+      "Android": TargetPlatform.android,
+      "iOS": TargetPlatform.iOS,
+    };
+    return Scaffold(
+      backgroundColor: Colors.white,
+      appBar: AppBar(
+        title: Text(widget.title),
+      ),
+      body: Container(
+        padding: const EdgeInsets.all(30),
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.start,
+          children: <Widget>[
+            Text(introText),
+            const SizedBox(height: 30),
+            Row(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                const Text("Force a platform:  "),
+                DropdownButton(
+                  value: selectedPlatform,
+                  items: List<DropdownMenuItem>.from(platforms.entries.map(
+                      (e) => DropdownMenuItem(
+                          value: e.value, child: Text(e.key)))),
+                  onChanged: (value) {
+                    setState(() {
+                      selectedPlatform = value;
+                    });
+                  },
+                ),
+              ],
+            ),
+            Row(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                const Text("Buttons:  "),
+                AdaptiveButton(
+                  forcePlatform: selectedPlatform,
+                  color: Colors.teal,
+                  onPressed: () {},
+                  child: const Text("I'm a button"),
+                ),
+              ],
+            ),
+            const SizedBox(height: 10),
+            Row(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                const Text("Dialogs:  "),
+                AdaptiveButton(
+                  forcePlatform: selectedPlatform,
+                  color: Colors.teal,
+                  onPressed: () {
+                    showDialog(
+                        context: context,
+                        builder: (context) {
+                          return AdaptiveDialog(
+                            title: "Test",
+                            content: const Text("This is the content area"),
+                            actions: [
+                              AdaptiveDialogAction(
+                                text: "Action 1",
+                                forcePlatform: selectedPlatform,
+                                onPressed: () {},
+                              ),
+                              AdaptiveDialogAction(
+                                text: "Action 2",
+                                forcePlatform: selectedPlatform,
+                                onPressed: () {},
+                              ),
+                            ],
+                            forcePlatform: selectedPlatform,
+                          );
+                        });
+                  },
+                  child: const Text("Show"),
+                ),
+              ],
+            ),
+            const SizedBox(height: 10),
+            Row(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                const Text("Loading Indicator:   "),
+                AdaptiveIndicator(
+                  forcePlatform: selectedPlatform,
+                ),
+              ],
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

using_platform_adaptive/lib/platform_adaptive.dart

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+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+
+abstract class PlatformAdaptiveWidget extends StatelessWidget {
+  const PlatformAdaptiveWidget({super.key, this.forcePlatform});
+
+  final TargetPlatform? forcePlatform;
+
+  @override
+  Widget build(BuildContext context) {
+    switch (forcePlatform ?? defaultTargetPlatform) {
+      case TargetPlatform.iOS:
+        return buildIOS(context);
+      default:
+        return buildAndroid(context);
+    }
+  }
+
+  Widget buildIOS(BuildContext context);
+  Widget buildAndroid(BuildContext context);
+}