ThemeData primarySwatch属性无法使用我的自定义MaterialColor

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // 自定义主题颜色
  final MaterialColor myCustomColor = MaterialColor(
    0xFF123456,
    <int, Color>{
      50: Color(0xFF123456),
      100: Color(0xFF123456),
      200: Color(0xFF123456),
      300: Color(0xFF123456),
      400: Color(0xFF123456),
      500: Color(0xFF123456),
      600: Color(0xFF123456),
      700: Color(0xFF123456),
      800: Color(0xFF123456),
      900: Color(0xFF123456),
    },
  );

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'My App',
      theme: ThemeData(
        primaryColor: myCustomColor, // 使用自定义主题颜色
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('My App'),
      ),
      body: Center(
        child: Text(
          'Hello, World!',
          style: TextStyle(
            color: Theme.of(context).primaryColor, // 使用主题颜色
          ),
        ),
      ),
    );
  }
}