在更新我的 mac OSX 10.10 之前，我一直在使用 cocapods。我再次尝试安装，但出现错误
ERROR: Error installing cocoapods:
ERROR: Failed to build gem native extension.
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby -rubygems /Library/Ruby/Gems/2.0.0/gems/rake-0.9.6/bin/rake RUBYARCHDIR=/Library/Ruby/Gems/2.0.0/extensions/universal-darwin-14/2.0.0/xcodeproj-0.17.0 RUBYLIBDIR=/Library/Ruby/Gems/2.0.0/extensions/universal-darwin-14/2.0.0/xcodeproj-0.17.0
/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/2.0.0/mkmf.rb:434: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/2.0.0/mkmf.rb:549:in `block in try_compile'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:502:in `with_werror'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:549:in `try_compile'
from extconf.rb:24:in `block in <main>'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:895:in `block in checking_for'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:340:in `block (2 levels) in postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:310:in `open'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:340:in `block in postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:310:in `open'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:336:in `postpone'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:894:in `checking_for'
from extconf.rb:23:in `<main>'
rake aborted!
Command failed with status (1): [/System/Library/Frameworks/Ruby.framework/...]
/Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.17.0/ext/xcodeproj/Rakefile:37:in `block in <top (required)>'
Tasks: TOP => default => ext
(See full trace by running task with --trace)
rake failed, exit code 1
Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/xcodeproj-0.17.0 for inspection.
Results logged to /Library/Ruby/Gems/2.0.0/extensions/universal-darwin-14/2.0.0/xcodeproj-0.17.0/gem_make.out