structure.js

import Iframe from "sanity-plugin-iframe-pane";

export const getDefaultDocumentNode = (S, { schemaType }) => {
  if (schemaType === "post") {
    return S.document().views([
      S.view.form(),
      S.view
        .component(Iframe)
        .options({
          // Required: Accepts an async function
          // OR a string
          url: `${
            process.env.NEXT_PUBLIC_VERCEL_URL || "http://localhost:3000"
          }/api/draft`,
          // Optional: Set the default size
          defaultSize: "desktop", // default "desktop"
          // Optional: Add a reload button, or reload on new document revisions
          reload: {
            button: true, // default "undefined"
          },
          // Optional: Pass attributes to the underlying 'iframe element:
          // See https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe
          attributes: {},
        })
        .title("Draft"),
    ]);
  }
};