The Core iOS Developer’s Cookbook, Fifth Edition

Core Motion Basics

The Core Motion framework centralizes access to the motion data generated by the iOS hardware. It provides monitoring of three key onboard sensors: the gyroscope, which measures device rotation; the magnetometer, which provides a way to measure compass bearings; and the accelerometer, which detects gravitational changes along three axes. A fourth entry point, called device motion, combines all three of these sensors into a single monitoring system.

Core Motion uses raw values from these sensors to create readable measurements, primarily in the form of force vectors. Measurable items include the following properties:

attitude ...