如何仅在react-final-form中初始化表单后才订阅字段更改

import React, { useEffect } from 'react';
import { Form, Field } from 'react-final-form';

const MyForm = () => {
  const onSubmit = (values) => {
    // 处理表单提交逻辑
  };

  useEffect(() => {
    const unsubscribe = form.subscribe(
      (values) => {
        // 处理字段更改逻辑
      },
      { values: true }
    );

    return unsubscribe;
  }, []);

  return (
    <Form onSubmit={onSubmit}>
      {({ handleSubmit }) => (
        <form onSubmit={handleSubmit}>
          <Field name="fieldName" component="input" type="text" />
          {/* 其他表单字段 */}
          <button type="submit">提交</button>
        </form>
      )}
    </Form>
  );
};

export default MyForm;