/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/dependency.rb:311:in `to_specs': Could not find 'ffi' (>= 1.3.0) among 86 total gem(s) (Gem::MissingSpecError)
Checked in 'GEM_PATH=/Users/flynnlee/.gem/ruby/2.6.0:/Library/Ruby/Gems/2.6.0:/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/gems/2.6.0', execute `gem env` for more information
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1449:in `block in activate_dependencies'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1438:in `each'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1438:in `activate_dependencies'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1420:in `activate'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1452:in `block in activate_dependencies'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1438:in `each'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1438:in `activate_dependencies'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1420:in `activate'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1452:in `block in activate_dependencies'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1438:in `each'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1438:in `activate_dependencies'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1420:in `activate'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1452:in `block in activate_dependencies'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1438:in `each'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1438:in `activate_dependencies'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1420:in `activate'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems.rb:304:in `block in activate_bin_path'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems.rb:303:in `synchronize'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems.rb:303:in `activate_bin_path'
    from /usr/local/bin/pod:23:in `<main>'

上面是我在使用时遇到的错误提醒，我解决的方法如下：

sudo gem install cocoapods-packager

这是安装最新的版本，如果需要其他版本的安装，可以加版本号

如：sudo gem install cocoapods-packager -v 1.5.0