TypeError when i used "pod packager"

[blackteachinese]

Error

TypeError - no implicit conversion of nil into String
/Library/Ruby/Gems/2.0.0/gems/cocoapods-core-1.1.1/lib/cocoapods-core/specification.rb:523:in `initialize'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-core-1.1.1/lib/cocoapods-core/specification.rb:523:in `new'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-core-1.1.1/lib/cocoapods-core/specification.rb:523:in `from_file'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-core-1.1.1/lib/cocoapods-core/specification/set.rb:45:in `specification'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-core-1.1.1/lib/cocoapods-core/source.rb:265:in `search'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-core-1.1.1/lib/cocoapods-core/source/aggregate.rb:83:in `block in search'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-core-1.1.1/lib/cocoapods-core/source/aggregate.rb:83:in `select'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-core-1.1.1/lib/cocoapods-core/source/aggregate.rb:83:in `search'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-core-1.1.1/lib/cocoapods-core/source/manager.rb:97:in `search'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-packager-1.5.0/lib/cocoapods-packager/pod_utils.rb:94:in `spec_with_name'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-packager-1.5.0/lib/cocoapods-packager/pod_utils.rb:79:in `block in binary_only?'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-packager-1.5.0/lib/cocoapods-packager/pod_utils.rb:79:in `map'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-packager-1.5.0/lib/cocoapods-packager/pod_utils.rb:79:in `binary_only?'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-packager-1.5.0/lib/pod/command/package.rb:53:in `validate!'
/Library/Ruby/Gems/2.0.0/gems/claide-1.0.1/lib/claide/command.rb:333:in `run'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-1.1.1/lib/cocoapods/command.rb:50:in `run'
/Library/Ruby/Gems/2.0.0/gems/cocoapods-1.1.1/bin/pod:55:in `<top (required)>'
/usr/local/bin/pod:22:in `load'
/usr/local/bin/pod:22:in `<main>'