• ERROR | license: Sample license type.
  s.license = { :type => "MIT", :file => "FILE_LICENSE" }

• ERROR | [OSX] unknown: Encountered an unknown error (The `itmSDK` pod failed to validate due to 1 error.
  [!] The validator for Swift projects uses Swift 3.0 by default, if you are using a different version of swift you can use a `.swift-version` file to set the version for your Pod. For example to use Swift 2.3, run:
  echo "2.3" > .swift-version:

It shows that because you're able to use both swift and Objc languages in your pod. Just run the following command in the terminal:

`echo "2.3" > .swift-version` 

Replace "2.3" with your current Swift version in XCode, if you're on 3.1 for example replace it with "3.1". It will create a swift version file in your pod-project folder. And then you can run the lint command to validate your podspec.

ERROR: While executing gem ... (Errno::EPERM)
Operation not permitted - /usr/bin/xcodeproj
sudo gem install -n /usr/local/bin cocoapods