之前添加国内ruby源 gem sources --add https://gems.ruby-china.org
报错：
ERROR: Could not find a valid gem 'cocoapods' (>= 0), here is why:
Unable to download data from http://gems.ruby-china.org - bad response Not Found 404 (https://gems.ruby-china.org/specs.4.8.gz)
原因是 ruby-china 更换了域名https://gems.ruby-china.com
命令替换为
gem sources --remove http://gems.ruby-china.org
gem sources --add https://gems.ruby-china.com
解决