我试图按照
http://cocoapods.org/的说明在mac上安装cocoapods,但得到的错误如下：
$sudo gem install cocoapods ERROR: While executing gem ... (Gem::RemoteFetcher::FetchError) bad response Service Unavailable: Back-end server is at capacity 503 (https://api.rubygems.org/api/v1/dependencies?gems=cocoapods)
但有时,错误信息是不同的.
$sudo gem install cocoapods Password: Building native extensions. This could take a while... ERROR: Error installing cocoapods: ERROR: Failed to build gem native extension. rake RUBYARCHDIR=/Users/tap4fun/.rvm/rubies/ruby-1.9.3-p484/lib/ruby/gems/1.9.1/extensions/x86_64-darwin-12/1.9.1/xcodeproj-0.17.0 RUBYLIBDIR=/Users/tap4fun/.rvm/rubies/ruby-1.9.3-p484/lib/ruby/gems/1.9.1/extensions/x86_64-darwin-12/1.9.1/xcodeproj-0.17.0/Users/tap4fun/.rvm/rubies/ruby-1.9.3-p484/lib/ruby/site_ruby/1.9.1/rubygems/dependency.rb:298:in `to_specs': Could not find 'rake' (>= 0) among 20 total gem(s) (Gem::LoadError) from /Users/tap4fun/.rvm/rubies/ruby-1.9.3-p484/lib/ruby/site_ruby/1.9.1/rubygems/dependency.rb:309:in `to_spec' from /Users/tap4fun/.rvm/rubies/ruby-1.9.3-p484/lib/ruby/site_ruby/1.9.1/rubygems/core_ext/kernel_gem.rb:53:in `gem' from /Users/tap4fun/.rvm/gems/ruby-1.9.3-p484/bin/rake:22:in `<main>' from /Users/tap4fun/.rvm/gems/ruby-1.9.3-p484/bin/ruby_executable_hooks:15:in `eval' from /Users/tap4fun/.rvm/gems/ruby-1.9.3-p484/bin/ruby_executable_hooks:15:in `<main>' rake Failed,exit code 1 Gem files will remain installed in /Users/tap4fun/.rvm/rubies/ruby-1.9.3- p484/lib/ruby/gems/1.9.1/gems/xcodeproj-0.17.0 for inspection. Results logged to /Users/tap4fun/.rvm/rubies/ruby-1.9.3-p484/lib/ruby/gems/1.9.1/extensions/x86_64-darwin-12/1.9.1/xcodeproj-0.17.0/gem_make.out
红宝石版本：1.9.3
rake版本：10.2.2
解决方法
试试这个(为OSX 10.10工作)
>打开Xcode 6
>打开首选项
>单击“位置”选项卡
>将命令行工具版本更改为Xcode 6.0
>卸载cocoapods
$sudo gem uninstall cocoapods
>安装xcodeproj
$sudo gem install xcodeproj
>安装cocoapods
$sudo gem install cocoapods
运行pod –version来验证