pod install-- JSON::ParserError - A JSON text must at least contain two octets!

解决办法1、

rm -rf "${HOME}/Library/Caches/CocoaPods"
rm -rf "pwd/Pods/"
pod update

Please backup the respective directories before running "rm" commands

解决办法2、

sudo gem uninstall cocoapods
sudo gem install cocoapods -v 1.7.5 或者 sudo gem install -n /usr/local/bin cocoapods -v 1.7.5