Step by step guide to integrate Twitter Bootstrap with Ruby on Rails application. Please note that after these steps, your application layout file will be replaced with default one.

Step1: Add gem to your Gemfile

gem 'twitter-bootstrap-rails'

Step 2: Install required gem. To do that, on terminal, run
bundle install

Step 3: Run bootstrap install scripts using following command

rails g bootstrap:install static

Step 4: Update application layouts

rails g bootstrap:layout [LAYOUT_NAME]
rails g bootstrap:layout application fixed
rails g bootstrap:layout application fluid

Step 5: To generate Bootstrap compatible scaffold views, use
rails g bootstrap:themed [RESOURCE_NAME]
rails g bootstrap:themed Restaurants

Be very careful that these generators will overwrite existing files thus removing previous content.

Step 6: Asset precompilation using
rake assets:precompile

Step 7: Don't forget to restart your application using
touch tmp/restart.txt