废物不多说直接看问题 

执行 sudo gem install -n /usr/local/bin cocoapods 遇到以下问题

Building native extensions. This could take a while...

ERROR:  Error installing cocoapods:

ERROR: Failed to build gem native extension.

    current directory: /Library/Ruby/Gems/2.3.0/gems/ffi-1.14.2/ext/ffi_c

/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby -r ./siteconf20210222-2752-1nsah5m.rb extconf.rb

mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/include/ruby.h

解决办法

open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

之后再次执行sudo gem install -n /usr/local/bin cocoapods 如还不行请执行

xcode-select --install

一直继续安装即可