升级到OS X Yosemite后，尝试安装pod会出现此错误。
/Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- xcodeproj/prebuilt/universal.x86_64-darwin14-2.0.0/xcodeproj_ext (LoadError)
from /Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.16.1/lib/xcodeproj/ext.rb:6:in `rescue in <top (required)>'
from /Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.16.1/lib/xcodeproj/ext.rb:3:in `<top (required)>'
from /Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.16.1/lib/xcodeproj.rb:30:in `<top (required)>'
from /Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Library/Ruby/Gems/2.0.0/gems/cocoapods-0.32.1/lib/cocoapods.rb:2:in `<top (required)>'
from /Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Library/Ruby/Gems/2.0.0/gems/cocoapods-0.32.1/bin/pod:32:in `<top (required)>'
from /usr/bin/pod:23:in `load'
from /usr/bin/pod:23:in `<main>'
我尝试卸载cocoapods并安装它没有运气。尝试安装cocoapods时出现此错误。
ERROR: While executing gem ... (Errno::EEXIST)
File exists @ dir_s_mkdir - /usr/local/Cellar/ruby/2.1.2/lib/ruby/gems
在xcode-preferences-locations中，我没有选择将命令行工具更改为低于Xcode 6.3的任何内容......
任何想法如何解决这个问题？