https://www.cnblogs.com/qinyan20/p/4221789.html
ruby-2.1.1 - #downloading rubygems-2.2.3
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- 0:00:01 --:--:-- 0curl: (22) The requested URL returned error: 404 Not Found
The requested url does not exist(22): 'http://production.cf.rubygems.org/rubygems/rubygems-2.2.3.tgz'
Checking fallback: ftp://production.cf.rubygems.org/rubygems/rubygems-2.2.3.tgz
Checking fallback: http://www.mirrorservice.org/sites/production.cf.rubygems.org/rubygems/rubygems-2.2.3.tgz
No fallback URL could be found, try increasing timeout with:
echo "export rvm_max_time_flag=20" >> ~/.rvmrc
There has been an error while trying to fetch rubygems.
Halting the installation.
Gemset '' does not exist, 'rvm ruby-2.1.1 do rvm gemset create ' first, or append '--create'.
解決代碼：
rvm get stable
RVM安裝pod 教程：
https://www.cnblogs.com/Evelyn-zn/p/5662967.html
https://www.cnblogs.com/Evelyn-zn/p/5662967.html