如何使用flutter将braintree集成到iOS或安卓应用？

dependencies:
  flutter_braintree: ^x.x.x # 使用最新版本号

pod 'Braintree'

dependencies {
    implementation 'com.braintreepayments.api:drop-in:4.x.x' // 使用最新版本号
}

import 'package:flutter_braintree/flutter_braintree.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('Braintree Example')),
        body: BraintreeExample(),
      ),
    );
  }
}

class BraintreeExample extends StatefulWidget {
  @override
  _BraintreeExampleState createState() => _BraintreeExampleState();
}

class _BraintreeExampleState extends State<BraintreeExample> {
  String _clientToken = '';

  @override
  void initState() {
    super.initState();
    _fetchClientToken();
  }

  Future<void> _fetchClientToken() async {
    // 这里应该从你的服务器获取client token
    // 以下是示例代码
    final response = await http.get(Uri.parse('https://your-server.com/token'));
    if (response.statusCode == 200) {
      setState(() {
        _clientToken = response.body;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Center(
      child: ElevatedButton(
        onPressed: _clientToken.isNotEmpty
            ? () => Navigator.of(context).push(
                MaterialPageRoute(builder: (context) => BraintreeScreen(clientToken: _clientToken)),
              )
            : null,
        child: Text('Pay with Braintree'),
      ),
    );
  }
}

class BraintreeScreen extends StatelessWidget {
  final String clientToken;

  BraintreeScreen({required this.clientToken});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Braintree Payment')),
      body: BraintreeDropIn(
        authorization: clientToken,
        onPaymentResult: (result) {
          // 处理支付结果
        },
      ),
    );
  }
}