dt_toolchain_dir cannot be used to evaluate library_search_paths, use toolchain_dir instead

Xcodeをアップデートしたらfirebaseでタイトルのエラーが表示されビルドエラーに、、

解決策は以下の通り

①podfileの一番下に「post_install do |installer|・・・」を追加

②ターミナルで、podfileの配下に移動して「pod init」を実行

# Uncomment the next line to define a global platform for your project
# platform :ios, '9.0'

target 'GarbageCalendar' do
  # Comment the next line if you don't want to use dynamic frameworks
  use_frameworks!

#  pod 'FSCalendar'

  pod 'RealmSwift'
  
  pod 'Firebase/Analytics'
  
  pod 'Firebase/Messaging'
  
  pod 'FirebaseAnalytics'
  
  pod 'FirebaseMessaging'
  
  pod 'Google-Mobile-Ads-SDK'

  # Pods for GarbageCalendar
end

post_install do |installer|
      installer.pods_project.targets.each do |target|
          target.build_configurations.each do |config|
          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
      end
  end