Suggestion for next edition of book


Joe and Aaron,

This chapter was well done.

A few hardware items of interest are worth noting here as well:

  • iPhone 4 and iTouch 4th generation have gyroscopes built into the device.
  • iPad, iPhone 4 and iTouch 4th gen. all have 12-bit resolution for their accelerometer data. Legacy devices have an 8-bit resolution. Something to consider if your filters are causing issues on older devices.

Session 423 talks about Device Motion which everyone should start transitioning to for the iOS4 platform. You can still use this new API to get to Accelerometer data on older devices.

Here is the URL but you must be a registered iPhone developer to access this link:



Thanks for the suggestions.

The recommended use of the gyroscope is to pull the current gyroscope reading from the hardware when you refresh the frame (or a similar timing mechanism). As frame rates and the usefullness of the gyroscope are tied closely to games, and our book focuses on application programming, I don’t think we will cover it.

However, the note on precision is worth mentioning.