今天pod install后出现了这样一个问题：
Ignoring byebug-10.0.2 because its extensions are not built. Try: gem pristine byebug --version 10.0.2
/Library/Ruby/Site/2.3.0/rubygems.rb:289:in `find_spec_for_exe': can't find gem cocoapods (>= 0.a) with executable pod (Gem::GemNotFoundException)
from /Library/Ruby/Site/2.3.0/rubygems.rb:308:in `activate_bin_path'
from /usr/local/bin/pod:23:in `<main>'
估计是我什么时候一不小心把cocoapods删了。
终端输入以下一条命令解决：
sudo gem install -n /usr/local/bin cocoapods
