Xcode 9 Podfile for supporting both Swift 3.2 and Swift 4 Cocoapods

Podfile

platform :ios, '9.3'

target 'target-name' do
  use_frameworks!
  pod 'AFNetworking', '~> 2'
  pod 'RSBarcodes_Swift', :git => 'https://github.com/yeahdongcn/RSBarcodes_Swift', :branch => 'master'
  
  swift3 = []
  swift4 = ['RSBarcodes_Swift'] # if these pods are in Swift 4
  
  post_install do |installer|
      installer.pods_project.targets.each do |target|
          swift_version = '3.2' if swift_32.include?(target.name)
          swift_version = '4.0' if swift4.include?(target.name)
          
          if swift_version
              target.build_configurations.each do |config|
                  config.build_settings['SWIFT_VERSION'] = swift_version
              end
          end
      end
  end
end