升级到mac 10.10之后使用pod出现问题的解决方法

最新对mac 10.10的强大功能好奇，于是将系统升级到了10.10，结果发现使用pod出现了下面的问题：

/system/library/frameworks/ruby.framework/versions/2.0/usr/lib/ruby/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 /system/library/frameworks/ruby.framework/versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
 from /library/ruby/gems/2.0.0/gems/xcodeproj-0.17.0/lib/xcodeproj/ext.rb:6:in `rescue in <top (required)>'
 from /library/ruby/gems/2.0.0/gems/xcodeproj-0.17.0/lib/xcodeproj/ext.rb:3:in `<top (required)>'
 from /system/library/frameworks/ruby.framework/versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
 from /system/library/frameworks/ruby.framework/versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
 from /library/ruby/gems/2.0.0/gems/xcodeproj-0.17.0/lib/xcodeproj.rb:30:in `<top (required)>'
 from /system/library/frameworks/ruby.framework/versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
 from /system/library/frameworks/ruby.framework/versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
 from /library/ruby/gems/2.0.0/gems/cocoapods-0.33.1/lib/cocoapods.rb:2:in `<top (required)>'
 from /system/library/frameworks/ruby.framework/versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
 from /system/library/frameworks/ruby.framework/versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require'
 from /library/ruby/gems/2.0.0/gems/cocoapods-0.33.1/bin/pod:32:in `<top (required)>'
 from /usr/bin/pod:23:in `load'
 from /usr/bin/pod:23:in `<main>'

经过一番乱搜，具体的解决步骤如下:
  1. 打开 xcode 6
  2. 进入 preferences
  3. 点击locations选项
  4. 将 command line tools 版本变成 xcode 6.0
  5. 卸载 cocoapods，在终端中输入

$ sudo gem uninstall cocoapods 

  6. 安装xcodeproj，在终端中输入

$ sudo gem install xcodeproj 

  7. 安装cocoapods，在终端中输入

$ sudo gem install cocoapods 

  8. 测试pod是否安装成功，在终端中输入

$ pod --version