Watch a video and read the full post including example code: http://www.zirthian.qubiqinteractive.ca/spaceship-control-and-physics.php
In this post I am going to talk abut two important things my arcade-style side-scroller shoot-'em up game: spaceship control and physics.
The game makes full use of the iOS's Sprite Kit Physics Engine. I must say working with this engine was a bit rough to start with, but once you understand what's going on, you can create amazing things and very believable behaviour with minimal code.