If anyone else is getting:
Unable to find a specification for … (libPusher in my case)
or the following:
Could not find cocoapods-0.19.1 in any of the sources
Pod::DSLError - Invalid Facebook-iOS-SDK.podspec file: undefined method `prepare_command=' for #
definitely try adding:
gem "cocoapods", '~> 0.23.0'
to your Gemfile, and then running:
pod setup && bundle update && bundle install
I guess there was a recent CocoaPods update that broke something with RubyMotion and motion-cocoapods.. or something.