Make your projects compatible with Xcode 14 & 15 at the same time

Podfile

platform :ios, '12.0'

# 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!

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

post_install do |installer|
  xcode_version = `xcodebuild -version | grep 'Xcode' | awk '{print $2}'`
  installer.pods_project.targets.each do |target|
    flutter_additional_ios_build_settings(target)
    target.build_configurations.each do |config|
      # Determine the Xcode version and mod the toolchain accordingly. 
      if xcode_version.strip >= '15.0'
        xcconfig_path = config.base_configuration_reference.real_path
        xcconfig = File.read(xcconfig_path)
        xcconfig_mod = xcconfig.gsub(/DT_TOOLCHAIN_DIR/, "TOOLCHAIN_DIR")
        File.open(xcconfig_path, "w") { |file| file << xcconfig_mod }
      end
      config.build_settings["EXCLUDED_ARCHS[sdk=iphonesimulator*]"] = 'i386 arm64'
    end
  end
end