transformer.js

const path = require("path");
const { getDefaultConfig } = require("expo/metro-config");

const expoTransformer = require(getDefaultConfig(process.cwd())
  .transformerPath);

exports.transformerPath = path.resolve(__filename);

exports.transform = async function transform(
  config,
  projectRoot,
  filename,
  data,
  options
) {
  if (
    path.dirname(filename) === config.cssInterop_outputDirectory &&
    !filename.endsWith(".css")
  ) {
    const injectedData =
      'import { __css } from "nativewind-size-matters/dist/index";' +
      'import { injectData } from "react-native-css-interop/dist/runtime/native/styles";' +
      "injectData(__css({}));";

    return expoTransformer.transform(
      config,
      projectRoot,
      filename,
      Buffer.from(injectedData),
      options
    );
  }

  return expoTransformer.transform(
    config,
    projectRoot,
    filename,
    data,
    options
  );
};