rails api docs

important one :

http://apionrails.icalialabs.com/book/chapter_one

its github
https://github.com/kurenn/market_place_api

User Authentication on iOS with Ruby on Rails and Swift

https://www.raywenderlich.com/85528/user-accounts-ios-ruby-rails-swift

github

https://github.com/subhransu/railsauth

some blogs

http://www.yoniweisbrod.com/rails-api-mini-guide/

https://labs.kollegorna.se/blog/2015/04/build-an-api-now/

http://www.andrewhavens.com/posts/20/beginners-guide-to-creating-a-rest-api/

https://codedecoder.wordpress.com/2013/02/21/sample-rest-api-example-in-rails/