我正在运行Mac OS X 10.10.2，尝试安装sanitize gem，我收到以下错误。我已经读过Nokogiri gem和Xcode存在某些问题。我该怎么做才能解决这个问题？
或者，是否有另一个宝石，我可以用来从字符串中剥离html？ （我只想要内容）。
libiconv is missing. please visit http://nokogiri.org/tutorials/installing_nokogiri.html for help with installing dependencies.
-----
*** 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.