Dart 层如何 兼容 Android 和iOS平台特性 ，阿里大神最佳总结Flutter进阶学习笔记

在Flutter中，为了在不同平台上编写具有特殊逻辑的代码，可以使用dart:io库来检查当前是Android还是iOS平台，或者使用package_info_plus插件来获取应用的包信息。

以下是一个简单的例子，演示如何根据平台特性来调整代码：

import 'package:flutter/foundation.dart' show kIsWeb;
import 'package:flutter/material.dart';
import 'package:package_info_plus/package_info_plus.dart';
 
void main() {
  runApp(MyApp());
}
 
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: PlatformSpecificWidget(),
    );
  }
}
 
class PlatformSpecificWidget extends StatefulWidget {
  @override
  _PlatformSpecificWidgetState createState() => _PlatformSpecificWidgetState();
}
 
class _PlatformSpecificWidgetState extends State<PlatformSpecificWidget> {
  String _platformVersion = 'Unknown';
 
  @override
  void initState() {
    super.initState();
    initPlatformState();
  }
 
  // Platform messages are asynchronous, so we initialize in an async method.
  Future<void> initPlatformState() async {
    String platformVersion;
    // Platform messages may fail, so we use a try/catch PlatformException.
    if (kIsWeb) {
      platformVersion = 'Web';
    } else {
      PackageInfo packageInfo = await PackageInfo.fromPlatform();
      platformVersion = packageInfo.buildNumber;
      if (Theme.of(context).platform == TargetPlatform.iOS) {
        platformVersion += 'iOS';
      } else {
        platformVersion += 'Android';
      }
    }
 
    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;
 
    setState(() {
      _platformVersion = platformVersion;
    });
  }
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Platform Specific Widget'),
      ),
      body: Center(
        child: Text('Running on $_platformVersion\n'),
      ),
    );
  }
}

在这个例子中，我们使用kIsWeb来检查是否在Web平台上运行，然后使用PackageInfo.fromPlatform()来获取应用的版本号。接着，我们检查当前的Theme.of(context).platform来判断是iOS还是Android平台，并相应地给_platformVersion赋值。最后，在界面上显示当前平台的信息。这样，无论是在Android设备还是iOS设备上，用户都能看到特定于他们平台的个性化信息。