错误信息如下

find_spec_for_exe': can't find gem cocoapods (>= 0.a) (Gem::GemNotFoundException)
from /Users/bastian/.rvm/rubies/ruby-2.3-head/lib/ruby/site_ruby/2.3.0/rubygems.rb:278:in activate_bin_path'
from /Users/bastian/bin/pod:22:in<main>'

解决办法

 mv ~/.gemrc ~/.gemrc_backup

 gem install cocoapods

上面两个命令解决问题