Use of unresolved identifier 'FirebaseApp' error?

Question

Apple Xcode

Ran into "Use of unresolved identifier 'FirebaseApp'" error when strictly following Firebase connection instructions from their site.

My version is Xcode 11.6 , IOS 11.0, Firebase 6.4.29 Tried

the following methods to fix the issue

1. pod repo update -> pod update -> pod install
   
2. import FirebaseCore instead of import Firebase
   
3. FIRApp.configure() instead of FirebaseApp.configure()
   
4. Shift+Cmnd+Alt+K
   
5. Project reopening
   
6. Restarting the computer
   
7. Reinstalling Firebase
   

At the moment the Podfile looks like this:

# Uncomment the next line to define a global platform for your project
# platform :ios, '11.0'

target 'Desavir1' do
  # Comment the next line if you don't want to use dynamic frameworks
  use_frameworks!
  
  # Add the Firebase pod for Google Analytics
  pod 'Firebase/Analytics'

  # Add the pods for any other Firebase products you want to use in your app
  # For example, to use Firebase Authentication and Cloud Firestore
  pod 'Firebase/Auth'
  pod 'Firebase/Firestore'
  pod 'Firebase/Database'
  # Pods for Desavir1

  target 'Desavir1Tests' do
    inherit! :search_paths
    # Pods for testing
  end


end

All the ways to fix this problem that I found on Google did not help, I don’t even know what to do next. Has anyone come across this problem and knows how to solve it?
/ Ps Periodically it turns out to get rid of the error and run the application, initialization in the Firebase console occurs, but when you press the cmnd + shift + alt + k keys, the error returns again. Also, when the error disappears, the "Auth.auth()" type module is still not available.