In this chapter, you've learned how to link the CoreMotion framework to handle accelerometer input and how to convert them into movement. As the game developed is a shoot 'em up, you had to configure the project to be oriented in a portrait mode and you learned how to calibrate the accelerometer data to position the device in a comfortable way.

To simulate depth and speed, you implemented the parallax effect using several concatenated backgrounds and two cloud layers scrolled at different velocities.

Then you discovered how to make your games look like films by adding particle systems and how to customize them to achieve the desired effect. I then introduced you to a useful tool to create these particle systems: Particle Designer.

You learned to create a class derived from CCSprite to configure the behavior of the enemies' spaceships, implementing two different init methods. Also, I showed you the common mistake made when removing objects from NSMutableArray and how to deal with it...