Based on the tutorials found in http://www.raywenderlich.com. I'm currently writing the code in Swift as a learning project.

Full Tutorials (objective-c): http://www.raywenderlich.com/62049/sprite-kit-tutorial-make-platform-game-like-super-mario-brothers-part-1 and http://www.raywenderlich.com/62053/sprite-kit-tutorial-make-platform-game-like-super-mario-brothers-part-2

Author of the original tutorial: Jake Gundersen, an indie game developer and runs the Indie Ambitions blog (http://indieambitions.com/)

Art: Vicky Wenderlich (http://www.gameartguppy.com/)