Can't install Rails on Mac OSX Lion

[dejohnny]

$ sudo gem install rails
Building native extensions. This could take a while...
ERROR: Error installing rails:
ERROR: Failed to build gem native extension.

/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb
mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/ruby.h


Gem files will remain installed in /Library/Ruby/Gems/1.8/gems/json-1.7.3 for inspection.
Results logged to /Library/Ruby/Gems/1.8/gems/json-1.7.3/ext/json/ext/parser/gem_make.out

[dejohnny]

On MAC OSX Lion 10.7.4, you need to install a special package installer called RailsInstaller.

RailsInstaller has everything you need to hit the ground running. It includes the following components:

Ruby 1.9.3-p194
Rails 3.2.6
Git 1.7.9.6
Sqlite 3070500
osx-gcc-installer 4.1
JewelryBox 1.3.0
RVM 1.14.2
SM 0.10.3

Get it here: railsinstaller.org/#osx

Play the video first before you proceed with the install.