Step 1:

flutter clean
rm -Rf ios/Pods
rm -Rf ios/.symlinks
rm -Rf ios/Flutter/Flutter.framework
rm -Rf ios/Flutter/Flutter.podspec
rm ios/Podfile

Step 2:

cd ios
flutter pub get
pod cache clean --all
pod install

    or  (below for m1 chip incase above command thrown error in pod install)

#1 Install ffi
sudo arch -x86_64 gem install ffi

#2 Re-install dependencies
arch -x86_64 pod install

Step 3:

1. Open ios/Pods/Pods.xcodeproj in Xcode
2. Change the iOS Deployment info from 8.0 to 9.0

Step 4:

From xcode clean / build again / run. Hope this should work. Before please confirm whether all the build settings for iOS configured properly or not.

Note: In those above steps i faced one more issue from Firebase like "firebase import not found". Below added steps how i solved.

Step 1: open ios/Podfile

Check platform :ios, '10.0' is uncommented

Step 2:

add below code at end of Podfile

target 'CustomImageNotifications' do
  use_frameworks!
  pod 'Firebase/Analytics'
  pod 'Firebase/Messaging'
end

Step 3: pod install & open xcode and clean / build.