gem source -r
gem source -a
gem install cocoapods
或者安装证书：
This is what solved it for me: Install this certificate:https://raw.githubusercontent.com/rubygems/rubygems/master/lib/rubygems/ssl_certs/AddTrustExternalCARoot-2048.pem
In this folder: {rubyfolder}\lib\ruby\2.1.0\rubygems\ssl_certs
This way you don't have to add insecure sources.
More info here: https://gist.github.com/luislavena/f064211759ee0f806c88