The iOS Simulator deployment targets is set to 7.0, but the range of supported deployment target version for this platform is 8.0 to 12.1

Question

You can set up your podfile to automatically match the deployment target of all the podfiles to your current project deployment target like this :

post_install do |installer|
 installer.pods_project.targets.each do |target|
  target.build_configurations.each do |config|
   config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'] = '9.0'
  end
 end
end

The problem is in your pod files deployment target iOS Version not in your project deployment target iOS Version, so you need to change the deployment iOS version for your pods as well to anything higher than 8.0 to do so open your project workspace and do this:

1- Click on pods.

2- Select each project and target and click on build settings.

3- Under Deployment section change the iOS Deployment Target version to anything more than 8.0 (better to try the same project version).

4- Repeat this for every other project in your pods then run the app.

see the photo for details

Instead of specifying a deployment target in pod post install, you can delete the pod deployment target for each pod, which causes the deployment target to be inherited from the Podfile.

You may need to run pod install for the effect to take place.

platform :ios, '12.0'

  post_install do |installer|
    installer.pods_project.targets.each do |target|
      target.build_configurations.each do |config|
        config.build_settings.delete 'IPHONEOS_DEPLOYMENT_TARGET'
      end
    end
  end

Iterating over the answer from Tao-Nhan Nguyen, accounting the original value set for every pod, adjusting it only if it's not greater than 8.0... Add the following to the Podfile:

post_install do |installer|
  installer.pods_project.targets.each do |target|
    target.build_configurations.each do |config|
      if Gem::Version.new('8.0') > Gem::Version.new(config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'])
        config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'] = '8.0'
      end
    end
  end
end