When we install cocoapods in MacOS like this:

➜  ~ sudo gem install cocoapods

we get this error:

Fetching: concurrent-ruby-1.1.7.gem (100%)
Successfully installed concurrent-ruby-1.1.7
Fetching: i18n-0.9.5.gem (100%)
Successfully installed i18n-0.9.5
Fetching: thread_safe-0.3.6.gem (100%)
Successfully installed thread_safe-0.3.6
Fetching: tzinfo-1.2.7.gem (100%)
Successfully installed tzinfo-1.2.7
Fetching: activesupport- (100%)
Successfully installed activesupport-
Fetching: nap-1.1.0.gem (100%)
Successfully installed nap-1.1.0
Fetching: fuzzy_match-2.0.4.gem (100%)
Successfully installed fuzzy_match-2.0.4
Fetching: httpclient-2.8.3.gem (100%)
Successfully installed httpclient-2.8.3
Fetching: algoliasearch-1.27.4.gem (100%)
Successfully installed algoliasearch-1.27.4
Fetching: ffi-1.13.1.gem (100%)
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 ./siteconf20201011-18064-1amwcon.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

When we look at the gem_make.out , we get this:

➜  ~ cat /Library/Ruby/Gems/2.3.0/extensions/universal-darwin-18/2.3.0/ffi-1.13.1/gem_make.out
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 ./siteconf20201011-18064-1amwcon.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


  • MacOS 10.14
  • Ruby 2.3.7p456 (2018-03-28 revision 63024) [universal.x86_64-darwin18]
  • Gem


According to this post, the reason is:

The issue is that Xcode 11 ships the macOS 10.15 SDK which includes headers for ruby2.6, but not for macOS 10.14’s ruby2.3.

Let check the ruby config:

➜  ~ ruby -rrbconfig -e 'puts RbConfig::CONFIG["rubyhdrdir"]'

➜  ~ ls -l /Applications/
ls: /Applications/ No such file or directory

You can see that , the output contains a directory(MacOSX10.15) that does not even exist!


We should fix this issue by updating the ruby config to the correct path:

➜  ~ sudo xcode-select --switch /Library/Developer/CommandLineTools
➜  ~ ruby -rrbconfig -e 'puts RbConfig::CONFIG["rubyhdrdir"]'

Let’s try again:

➜  ~ sudo gem install cocoapods
Building native extensions.  This could take a while...
Successfully installed ffi-1.13.1
Fetching: ethon-0.12.0.gem (100%)
Successfully installed ethon-0.12.0
Fetching: typhoeus-1.4.0.gem (100%)
Successfully installed typhoeus-1.4.0
Fetching: netrc-0.11.0.gem (100%)
Successfully installed netrc-0.11.0
Fetching: cocoapods-core-1.9.3.gem (100%)
Successfully installed cocoapods-core-1.9.3
Fetching: claide-1.0.3.gem (100%)
Successfully installed claide-1.0.3
Fetching: cocoapods-deintegrate-1.0.4.gem (100%)
Successfully installed cocoapods-deintegrate-1.0.4
Fetching: cocoapods-downloader-1.4.0.gem (100%)
Successfully installed cocoapods-downloader-1.4.0
Fetching: cocoapods-plugins-1.0.0.gem (100%)
Successfully installed cocoapods-plugins-1.0.0
Fetching: cocoapods-search-1.0.0.gem (100%)
Successfully installed cocoapods-search-1.0.0
Fetching: cocoapods-stats-1.1.0.gem (100%)
Successfully installed cocoapods-stats-1.1.0
Fetching: cocoapods-trunk-1.5.0.gem (100%)
Successfully installed cocoapods-trunk-1.5.0
Fetching: cocoapods-try-1.2.0.gem (100%)
Successfully installed cocoapods-try-1.2.0
Fetching: molinillo-0.6.6.gem (100%)
Successfully installed molinillo-0.6.6
Fetching: atomos-0.1.3.gem (100%)
Successfully installed atomos-0.1.3
Fetching: CFPropertyList-3.0.2.gem (100%)
Successfully installed CFPropertyList-3.0.2
Fetching: colored2-3.1.2.gem (100%)
Successfully installed colored2-3.1.2
Fetching: nanaimo-0.3.0.gem (100%)
Successfully installed nanaimo-0.3.0
Fetching: xcodeproj-1.19.0.gem (100%)
Successfully installed xcodeproj-1.19.0
Fetching: escape-0.0.4.gem (100%)
Successfully installed escape-0.0.4
Fetching: fourflusher-2.3.1.gem (100%)
Successfully installed fourflusher-2.3.1
Fetching: gh_inspector-1.1.3.gem (100%)
Successfully installed gh_inspector-1.1.3
Fetching: ruby-macho-1.4.0.gem (100%)
Successfully installed ruby-macho-1.4.0
Fetching: cocoapods-1.9.3.gem (100%)
Successfully installed cocoapods-1.9.3
Parsing documentation for ffi-1.13.1
Installing ri documentation for ffi-1.13.1
Parsing documentation for ethon-0.12.0
Installing ri documentation for ethon-0.12.0
Parsing documentation for typhoeus-1.4.0
Installing ri documentation for typhoeus-1.4.0
Parsing documentation for netrc-0.11.0
Installing ri documentation for netrc-0.11.0
Parsing documentation for cocoapods-core-1.9.3
Installing ri documentation for cocoapods-core-1.9.3
Parsing documentation for claide-1.0.3
Installing ri documentation for claide-1.0.3
Parsing documentation for cocoapods-deintegrate-1.0.4
Installing ri documentation for cocoapods-deintegrate-1.0.4
Parsing documentation for cocoapods-downloader-1.4.0
Installing ri documentation for cocoapods-downloader-1.4.0
Parsing documentation for cocoapods-plugins-1.0.0
Installing ri documentation for cocoapods-plugins-1.0.0
Parsing documentation for cocoapods-search-1.0.0
Installing ri documentation for cocoapods-search-1.0.0
Parsing documentation for cocoapods-stats-1.1.0
Installing ri documentation for cocoapods-stats-1.1.0
Parsing documentation for cocoapods-trunk-1.5.0
Installing ri documentation for cocoapods-trunk-1.5.0
Parsing documentation for cocoapods-try-1.2.0
Installing ri documentation for cocoapods-try-1.2.0
Parsing documentation for molinillo-0.6.6
Installing ri documentation for molinillo-0.6.6
Parsing documentation for atomos-0.1.3
Installing ri documentation for atomos-0.1.3
Parsing documentation for CFPropertyList-3.0.2
Installing ri documentation for CFPropertyList-3.0.2
Parsing documentation for colored2-3.1.2
Installing ri documentation for colored2-3.1.2
Parsing documentation for nanaimo-0.3.0
Installing ri documentation for nanaimo-0.3.0
Parsing documentation for xcodeproj-1.19.0
Installing ri documentation for xcodeproj-1.19.0
Parsing documentation for escape-0.0.4
Installing ri documentation for escape-0.0.4
Parsing documentation for fourflusher-2.3.1
Installing ri documentation for fourflusher-2.3.1
Parsing documentation for gh_inspector-1.1.3
Installing ri documentation for gh_inspector-1.1.3
Parsing documentation for ruby-macho-1.4.0
Installing ri documentation for ruby-macho-1.4.0
Parsing documentation for cocoapods-1.9.3
Installing ri documentation for cocoapods-1.9.3
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 43 seconds
24 gems installed
➜  ~

The last step

Since we changed the xcode settings, we should restore it:

➜  ~ sudo xcode-select --switch /Applications/

xcode-select is a command-line utility on OS X that facilitates switching between different sets of command line developer tools provided by Apple. Its primary function is to be a “master switch” for the actual paths resolved when invoking the commands for tools like make , xcodebuild , otool , etc

Ok, everything is done.