# CMGyroData Class Reference

## Overview

An instance of the `CMGyroData`

class contains a single measurement of the device’s rotation rate.

An application receives or samples `CMGyroData`

objects at regular intervals after calling the `startGyroUpdatesToQueue:withHandler:`

method or the `startGyroUpdates`

method of the `CMMotionManager`

class.

## Properties

### rotationRate

The rotation rate as measured by the device’s gyroscope. (read-only)

##### Discussion

This property yields a measurement of the device’s rate of rotation around three axes. Whereas this property gives the raw data from the gyroscope, the identically named property of `CMDeviceMotion`

gives a `CMRotationRate`

structure measuring gyroscope data whose bias has been removed by Core Motion algorithms.

##### Availability

- Available in iOS 4.0 and later.

##### Declared In

`CMGyro.h`

## Constants

### CMRotationRate

The type of structures representing a measurement of rotation rate.

typedef struct { double x; double y; double z; } CMRotationRate

##### Constants

`x`

The X-axis rotation rate in radians per second. The sign follows the right hand rule: If the right hand is wrapped around the X axis such that the tip of the thumb points toward positive X, a positive rotation is one toward the tips of the other four fingers.

`y`

The Y-axis rotation rate in radians per second. The sign follows the right hand rule: If the right hand is wrapped around the Y axis such that the tip of the thumb points toward positive Y, a positive rotation is one toward the tips of the other four fingers.

`z`

The Z-axis rotation rate in radians per second. The sign follows the right hand rule: If the right hand is wrapped around the Z axis such that the tip of the thumb points toward positive Z, a positive rotation is one toward the tips of the other four fingers.

##### Availability

- Available in iOS 4.0 and later.

##### Declared In

`CMGyro.h`

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