/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby -rubygems /Library/Ruby/Gems/2.0./gems/rake-0.9./bin/rake RUBYARCHDIR=/Library/Ruby/Gems/2.0./extensions/universal-darwin-/2.0./xcodeproj-0.17. RUBYLIBDIR=/Library/Ruby/Gems/2.0./extensions/universal-darwin-/2.0./xcodeproj-0.17.

/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb

checking for -std=c99 option to compiler... *** extconf.rb failed ***

Could not create Makefile due to some reason, probably lack of necessary

libraries and/or headers.  Check the mkmf.log file for more details.  You may

need configuration options.

Provided configuration options:

    --with-opt-dir

    --without-opt-dir

    --with-opt-include

    --without-opt-include=${opt-dir}/include

    --with-opt-lib

    --without-opt-lib=${opt-dir}/lib

    --with-make-prog

    --without-make-prog

    --srcdir=.

    --curdir

    --ruby=/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby

/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0./mkmf.rb::in `try_do': The compiler failed to generate an executable file. (RuntimeError)

You have to install development tools first.

    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0./mkmf.rb::in `block in try_compile'

    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0./mkmf.rb::in `with_werror'

    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0./mkmf.rb::in `try_compile'

    from extconf.rb::in `block in <main>'

    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0./mkmf.rb::in `block in checking_for'

    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0./mkmf.rb::in `block ( levels) in postpone'

    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0./mkmf.rb::in `open'

    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0./mkmf.rb::in `block in postpone'

    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0./mkmf.rb::in `open'

    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0./mkmf.rb::in `postpone'

    from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0./mkmf.rb::in `checking_for'

    from extconf.rb::in `<main>'

rake aborted!

Command failed with status (): [/System/Library/Frameworks/Ruby.framework/...]

/Library/Ruby/Gems/2.0./gems/xcodeproj-0.17./ext/xcodeproj/Rakefile::in `block in <top (required)>'

Tasks: TOP => default => ext

(See full trace by running task with --trace)

首先安装Xcode6 的 Command Line Tools，在开发者中心下载

接下来按照下面步骤操作：

打开 Xcode

打开 Preferences

选择 Locations 选项卡

将 Command Line Tools 选择为 Xcode 6.0

卸载 cocoapods

$ sudo gem uninstall cocoapods

安装 xcodeproj

$ sudo gem install xcodeproj

再安装 cocoapods

$ sudo gem install cocoapods

最后运行 pod --version 就看到Pod正常了。