[Mac|gem]Failed to build gem native extension

Mac 10.14.4安装cocoapods报错

$ sudo gem install cocoapods
Password:
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-1.13.1/ext/ffi_c
/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby -r ./siteconf20200703-21484-ad0bg7.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

extconf failed, exit code 1

Gem files will remain installed in /Library/Ruby/Gems/2.3.0/gems/ffi-1.13.1 for inspection.
Results logged to /Library/Ruby/Gems/2.3.0/extensions/universal-darwin-18/2.3.0/ffi-1.13.1/gem_make.out

升级gem

$ sudo gem update --system

重新安装即可