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# CMDeviceMotion

Encapsulated measurements of the attitude, rotation rate, and acceleration of a device.

```
class CMDeviceMotion
```

## Overview

An application receives or samples `CMDeviceMotion` objects at regular intervals after calling the [`startDeviceMotionUpdates(using:to:withHandler:)`](/documentation/CoreMotion/CMMotionManager/startDeviceMotionUpdates(using:to:withHandler:)) method, the [`startDeviceMotionUpdates(to:withHandler:)`](/documentation/CoreMotion/CMMotionManager/startDeviceMotionUpdates(to:withHandler:)) method, the [`startDeviceMotionUpdates(using:)`](/documentation/CoreMotion/CMMotionManager/startDeviceMotionUpdates(using:)) method, or the [`startDeviceMotionUpdates()`](/documentation/CoreMotion/CMMotionManager/startDeviceMotionUpdates()) method of the [`CMMotionManager`](/documentation/CoreMotion/CMMotionManager) class.

The accelerometer measures the sum of two acceleration vectors: gravity and user acceleration. User acceleration is the acceleration that the user imparts to the device. Because Core Motion is able to track a device’s attitude using both the gyroscope and the accelerometer, it can differentiate between gravity and user acceleration. A `CMDeviceMotion` object provides both measurements in the [`gravity`](/documentation/CoreMotion/CMDeviceMotion/gravity) and [`userAcceleration`](/documentation/CoreMotion/CMDeviceMotion/userAcceleration) properties.

## Topics

### Getting Attitude and Rotation Rate

[`attitude`](/documentation/CoreMotion/CMDeviceMotion/attitude)

The attitude of the device.

[`rotationRate`](/documentation/CoreMotion/CMDeviceMotion/rotationRate)

The rotation rate of the device.

### Getting Acceleration Data

[`gravity`](/documentation/CoreMotion/CMDeviceMotion/gravity)

The gravity acceleration vector expressed in the device’s reference frame.

[`userAcceleration`](/documentation/CoreMotion/CMDeviceMotion/userAcceleration)

The acceleration that the user is giving to the device.

### Getting the Calibrated Magnetic Field

[`magneticField`](/documentation/CoreMotion/CMDeviceMotion/magneticField)

Returns the magnetic field vector with respect to the device.

[`CMCalibratedMagneticField`](/documentation/CoreMotion/CMCalibratedMagneticField)

Calibrated magnetic field data and an estimate of the accuracy of the calibration.

[`CMMagneticFieldCalibrationAccuracy`](/documentation/CoreMotion/CMMagneticFieldCalibrationAccuracy)

Indicates the calibration accuracy of a magnetic field estimate

### Getting the Heading

[`heading`](/documentation/CoreMotion/CMDeviceMotion/heading)

The heading angle (measured in degrees) relative to the current reference frame.

### Getting the Sensor Location

[`sensorLocation`](/documentation/CoreMotion/CMDeviceMotion/sensorLocation-swift.property)

The location of the sensors that compute the device-motion data.

[`CMDeviceMotion.SensorLocation`](/documentation/CoreMotion/CMDeviceMotion/SensorLocation-swift.enum)

Defines the device’s sensor locations.


---

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