[Xcode] pod 설치에러 CocoaPods

$sudo gem install cocoapods
Fetching: httpclient-2.8.3.gem (100%)
Successfully installed httpclient-2.8.3
Fetching: algoliasearch-1.27.1.gem (100%)
Successfully installed algoliasearch-1.27.1
Fetching: ffi-1.12.2.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-1.12.2/ext/ffi_c
/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby -r ./siteconf20200401-48828-flwofy.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

라며 에러를 뱉고 있어서 열심히 구글링해보니

MAC 버젼 오류였음.. Mojave에서는 저렇게 최신버젼 설치하면 에러남.

그냥 1.8.4로 설치해서 해결완료

sudo gem install cocoapods -v 1.8.4
Fetching: cocoapods-core-1.8.4.gem (100%)
Successfully installed cocoapods-core-1.8.4
Fetching: cocoapods-trunk-1.4.1.gem (100%)
Successfully installed cocoapods-trunk-1.4.1
Fetching: fourflusher-2.3.1.gem (100%)
Successfully installed fourflusher-2.3.1
Fetching: cocoapods-1.8.4.gem (100%)
Successfully installed cocoapods-1.8.4
Parsing documentation for cocoapods-core-1.8.4
Installing ri documentation for cocoapods-core-1.8.4
Parsing documentation for cocoapods-trunk-1.4.1
Installing ri documentation for cocoapods-trunk-1.4.1
Parsing documentation for fourflusher-2.3.1
Installing ri documentation for fourflusher-2.3.1
Parsing documentation for cocoapods-1.8.4
Installing ri documentation for cocoapods-1.8.4
Done installing documentation for cocoapods-core, cocoapods-trunk, fourflusher, cocoapods after 8 seconds
4 gems installed