Podfile sample of a Flutter project.

Podfile

# Uncomment this line to define a global platform for your project
platform :ios, '13.0'

# CocoaPods analytics sends network stats synchronously affecting flutter build latency.
ENV['COCOAPODS_DISABLE_STATS'] = 'true'

project 'Runner', {
  'Debug' => :debug,
  'Profile' => :release,
  'Release' => :release,
}

def flutter_root
  generated_xcode_build_settings_path = File.expand_path(File.join('..', 'Flutter', 'Generated.xcconfig'), __FILE__)
  unless File.exist?(generated_xcode_build_settings_path)
    raise "#{generated_xcode_build_settings_path} must exist. If you're running pod install manually, make sure flutter pub get is executed first"
  end

  File.foreach(generated_xcode_build_settings_path) do |line|
    matches = line.match(/FLUTTER_ROOT\=(.*)/)
    return matches[1].strip if matches
  end
  raise "FLUTTER_ROOT not found in #{generated_xcode_build_settings_path}. Try deleting Generated.xcconfig, then run flutter pub get"
end

require File.expand_path(File.join('packages', 'flutter_tools', 'bin', 'podhelper'), flutter_root)

flutter_ios_podfile_setup

target 'Runner' do
  use_frameworks!
  use_modular_headers!

  # The following line is because of: https://firebase.flutter.dev/docs/overview/#improve-ios-build-times
  # Find the latest tag from: https://github.com/invertase/firestore-ios-sdk-frameworks#supported-firebase-ios-sdk-versions
  # Also, in case you change the version here then make sure you update the web.html file, too.
  pod 'FirebaseFirestore', :git => 'https://github.com/invertase/firestore-ios-sdk-frameworks.git', :tag => '9.3.0'

  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
end

post_install do |installer|
  installer.pods_project.targets.each do |target|
    flutter_additional_ios_build_settings(target)
    target.build_configurations.each do |config|
      config.build_settings['EXPANDED_CODE_SIGN_IDENTITY'] = ""
      config.build_settings['CODE_SIGNING_REQUIRED'] = "NO"
      config.build_settings['CODE_SIGNING_ALLOWED'] = "NO"
      
      # This is very important to have IPHONEOS_DEPLOYMENT_TARGET. Deleting the line fails the build on CI system.
      config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'] = '13.0'
    end
  end
end