I solved this problem with using brew
You need to:
install LATEST version of brew (https://treehouse.github.io/installation-guides/mac/homebrew)
then use "brew uninstall cocoapods"
install the latest version of cocoapods using "brew install cocoapods" (You must verify installed version with github version https://github.com/CocoaPods/CocoaPods/releases/tag/1.11.2, they must match)
overwrite link to cocoapods with "brew link --overwrite cocoapods"
check the version of cocoapods "pod --version"
done, You have the latest version of cocoapods installed