我正在尝试将 cocoapods 安装到运行 OSX 10.9.1（新 Mavericks）的 MacBook Pro 上，输入后gem install cocoapods出现以下错误：

    Building native extensions.  This could take a while...
ERROR:  Error installing cocoapods:
    ERROR: Failed to build gem native extension.

        "/usr/local/rvm/rubies/ruby-1.9.3-p194/bin/ruby" -rubygems /usr/local/rvm/gems/ruby-1.9.3-p194/gems/rake-10.1.1/bin/rake RUBYARCHDIR=/Users/rangreenberg/gems/gems/xcodeproj-0.14.1/ext RUBYLIBDIR=/Users/rangreenberg/gems/gems/xcodeproj-0.14.1/ext
/usr/local/rvm/rubies/ruby-1.9.3-p194/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
    --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=/usr/local/rvm/rubies/ruby-1.9.3-p194/bin/ruby
/usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:381:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
    from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:491:in `block in try_compile'
    from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:443:in `with_werror'
    from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:491:in `try_compile'
    from extconf.rb:24:in `block in <main>'
    from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:790:in `block in checking_for'
    from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:284:in `block (2 levels) in postpone'
    from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:254:in `open'
    from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:284:in `block in postpone'
    from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:254:in `open'
    from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:280:in `postpone'
    from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:789:in `checking_for'
    from extconf.rb:23:in `<main>'
rake aborted!
Command failed with status (1): [/usr/local/rvm/rubies/ruby-1.9.3-p194/bin/...]

Tasks: TOP => default => ext
(See full trace by running task with --trace)


Gem files will remain installed in /Users/rangreenberg/gems/gems/xcodeproj-0.14.1 for inspection.
Results logged to /Users/rangreenberg/gems/gems/xcodeproj-0.14.1/ext/xcodeproj/gem_make.out