When I try to run the command "pod init" it gives me error command not found. After that I try to run the command "sudo gem install cocoapods" then it again gives me error "Failed to build gem native extension" with this message
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 ./siteconf20200701-1901-10omoap.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.
I could not understand the problem.
My Xcode version is 11.3.