Please specify a platform for this target in your Podfile?

Replace your whole pod file text with below text and then check.

# Uncomment the next line to define a global platform for your project

# platform :ios, '9.0'

target 'testing_gowtham' do

use_frameworks!


pod 'Firebase/Core'
pod 'Firebase/Firestore'
end

(or) solution 2

platform :ios, '9.0' is working...I simply removed # this

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

target 'testing_gowtham' do
  # Comment the next line if you're not using Swift and don't want to use dynamic frameworks
  use_frameworks!

  # Pods for testing_gowtham
 pod 'Firebase/Core'
 pod 'Firebase/Firestore'

end

There are Three ways to fix it

1. BREAKING FEAT: forward port to firebase-ios-sdk v7.3.0.

• Due to this SDK upgrade, iOS 10 is now the minimum supported version by FlutterFire. Please update your build target version.

  Solution:

  Go to the file ios/Podfile inside your project, and uncomment


  # platform :ios, '9.0'
  

  Then change the version to 10


  platform :ios, '10.0'
  

2. Go to the file ios/Podfile inside your project, find there the line

   # platform :ios, '9.0' // and uncomment it. 
   

   After uncommenting your Podfile will seems like this

   # Uncomment the next line to define a global platform for your project
    platform :ios, '9.0'
   
   target 'testing_gowtham' do
   # Comment the next line if you're not using Swift and don't want to use 
    dynamic frameworks
    use_frameworks!
   
   # Pods for testing_gowtham
    pod 'Firebase/Core'
    pod 'Firebase/Firestore'
   end
   

   After that delete ios/Podfile.lock file and run pod install

3. Follow these commands in the terminal to fix the issue :

   gem uninstall cocoapods
   gem install cocoapods
   rm Podfile.lock
   pod setup
   pod install
   

If you have installed rvm as the root user, then you must sudo to install anything. like sudo gem uninstall cocoapods