On macOS Catalina I faced several issues install cocoapods, and below is the solution.
sudo gem install -n /usr/local/bin cocoapods Building native extensions. This could take a while... ERROR: Error installing cocoapods: ERROR: Failed to build gem native extension. current directory: /Library/Ruby/Gems/2.6.0/gems/ffi-1.12.2/ext/ffi_c /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby -I /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0 -r ./siteconf20200416-2584-hct4l8.rb extconf.rb mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/include/ruby.h You might have to install separate package for the ruby development environment, ruby-dev or ruby-devel for example. extconf failed, exit code 1 Gem files will remain installed in /Library/Ruby/Gems/2.6.0/gems/ffi-1.12.2 for inspection. Results logged to /Library/Ruby/Gems/2.6.0/extensions/universal-darwin-19/2.6.0/ffi-1.12.2/gem_make.out ameedjamous@Ameeds-iMac O2IOS-master % sudo gem install -n /usr/local/bin ruby-dev ERROR: Could not find a valid gem 'ruby-dev' (>= 0) in any repository ERROR: Possible alternatives: ruby_dev ameedjamous@Ameeds-iMac O2IOS-master % sudo gem install -n /usr/local/bin ruby-devel ERROR: Could not find a valid gem 'ruby-devel' (>= 0) in any repository ERROR: Possible alternatives: ruby_dev, rubdev, ruby-DTL, ruby-avl, ruby-d2l
# brew cleanup -d -v # brew install cocoapods
Thought others might find this useful.