虽然defaultTargetPlatform可以工作，但我建议使用Theme.of(context). targetplatform。这样可以测试iOS行为(因为defaultTargetPlatform总是TargetPlatform)。Android正在测试中)。它还允许小部件的祖先通过将其包装在Theme小部件中来覆盖其目标平台。

**multiple platform you check and run your code according specific platform **

bool isIOS = Theme.of(context).platform == TargetPlatform.iOS;
bool isAndroid = Theme.of(context).platform == TargetPlatform.android;
bool islinux = Theme.of(context).platform == TargetPlatform.linux;
bool isfuchsia = Theme.of(context).platform == TargetPlatform.fuchsia;
bool isMacOS = Theme.of(context).platform == TargetPlatform.macOS;
bool iswindows = Theme.of(context).platform == TargetPlatform.windows;

import 'dart:io' show Platform;

if (Platform.isAndroid) {
  // Android-specific code
} else if (Platform.isIOS) {
  // iOS-specific code
}else if (Platform.isFuchsia) {
  // Fuchsia-specific code
}else if (Platform.isLinux) {
  // Linux-specific code
}else if (Platform.isMacOS) {
  // MacOS-specific code
}else if (Platform.isWindows) {
  // Windows-specific code
}else if (Platform.isWindows) {
  // Windows-specific code
}

网络

import 'package:flutter/foundation.dart' show kIsWeb;

if (kIsWeb) {
  // running on the web!
} else {
  // NOT running on the web! You can check for additional platforms here.
}

所以这里有一个小工具，我用来检测平台和操作系统的反应适当。

import'dart:io' show Platform;
import 'package:flutter/foundation.dart' show kIsWeb;

class Util {

  os getPlatform() {
    if (kIsWeb) {
      return os.Web;
    } else if (Platform.isIOS) {
      return os.IOS;
    } else if (Platform.isAndroid) {
      return os.Android;
    } else if (Platform.isFuchsia) {
      return os.Fuchsia;
    } else if (Platform.isLinux) {
      return os.Linux;
    } else if (Platform.isMacOS) {
      return os.MacOS;
    } else if (Platform.isWindows) {
      return os.Windows;
    }
    return os.Unknown;
  }

  bool isWeb() {
    return (getPlatform()==os.Web);
  }

  bool isMobile() {
    os platform = getPlatform();
    return (platform == os.Android || platform == os.IOS || platform== os.Fuchsia);
  }

  bool isComputer() {
    os platform = getPlatform();
    return (platform == os.Linux || platform == os.MacOS || platform== os.Windows);
  }

}

enum os { Unknown, Web, Android, Fuchsia, IOS, Linux, MacOS, Windows }

感谢科林，最终答案是:

bool isIOS = Theme.of(context).platform == TargetPlatform.iOS;

如果你同时导入"dart:io"和"dart:html"，它不知道要导入哪个平台并给出错误。导入其中一个。

import 'dart:io';
Platform.isIOS ? CupertinoWidget() : MaterialWidget()