Example of expo config plugin for modifying Podfile

expo-config-plugin-modify-pod.ts

import { ConfigPlugin, withDangerousMod } from '@expo/config-plugins'
import {
  MergeResults,
  mergeContents,
  removeContents,
} from '@expo/config-plugins/build/utils/generateCode'
import path from 'path'
import fs from 'fs-extra'

const debug = require('debug')('file-viewer-plugin') as typeof console.log

export function addExcludedArm64(src: string): MergeResults {
  return mergeContents({
    tag: 'add-arm64',
    src,
    newSrc: `
    installer.pods_project.build_configurations.each do |config|
      config.build_settings["EXCLUDED_ARCHS[sdk=iphonesimulator*]"] = "arm64"
    end`,
    anchor: /__apply_Xcode_12_5_M1_post_install_workaround\(installer\)/,
    offset: 1,
    comment: '#',
  })
}

const withExcludedArm64: ConfigPlugin = config => {
  return withDangerousMod(config, [
    'ios',
    async config => {
      const filePath = path.join(config.modRequest.platformProjectRoot, 'Podfile')
      const contents = await fs.readFile(filePath, 'utf-8')
      let results: MergeResults
      if (contents.indexOf('config.build_settings["EXCLUDED_ARCHS[sdk=iphonesimulator*]"] = "arm64"') > -1) {
        return config
      }
      else {
        try {
          results = addExcludedArm64(contents)
        } catch (error: any) {
          if (error.code === 'ERR_NO_MATCH') {
            throw new Error(
              `Cannot add arm64 from project's ios/Podfile because it's malformed. Please report this with a copy of your project Podfile.`
            )
          }
          throw error
        }
  
        if (results.didMerge || results.didClear) {
          await fs.writeFile(filePath, results.contents)
        }
        return config
      }
      
    },
  ])
}


const initPlugin: ConfigPlugin = config => {
  config = withExcludedArm64(config)
  return config
}

export default initPlugin