报错Failed to build gem native extension.

环境

mac系统版本：macOS Mojave10.14.6
ruby:ruby 2.3.7p456 (2018-03-28 revision 63024)
cocoapods: 1.5.0

issue

拿到一个新项目(cocoapods 1.9.0)，使用sudo gem install cocoapods更新仓库！报错如下：

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-1.12.2/ext/ffi_c
/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby -r ./siteconf20200309-13044-14m1r7i.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-1.12.2 for inspection.
Results logged to /Library/Ruby/Gems/2.3.0/extensions/universal-darwin-18/2.3.0/ffi-1.12.2/gem_make.out

尝试了gem update --system、xcode-select --install、sudo apt-get install ruby-dev等方法未解决该问题！

解决方法

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

Done installing documentation for ffi, 
ethon, typhoeus, netrc, cocoapods-core, claide,
 cocoapods-deintegrate, cocoapods-downloader, 
cocoapods-plugins, cocoapods-search, 
cocoapods-stats, cocoapods-trunk, cocoapods-try,
 molinillo, atomos, CFPropertyList, colored2,
 nanaimo, xcodeproj, escape, fourflusher, gh_inspector, 
ruby-macho, cocoapods after 50 seconds
24 gems installed

参考链接