<!--
{
  "availability" : [
    "iOS: 8.0.0 -",
    "iPadOS: 8.0.0 -",
    "macCatalyst: 13.1.0 -",
    "watchOS: 2.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "CoreMotion",
  "identifier" : "/documentation/CoreMotion/CMAltitudeData",
  "metadataVersion" : "0.1.0",
  "role" : "Class",
  "symbol" : {
    "kind" : "Class",
    "modules" : [
      "Core Motion"
    ],
    "preciseIdentifier" : "c:objc(cs)CMAltitudeData"
  },
  "title" : "CMAltitudeData"
}
-->

# CMAltitudeData

Data for a recorded change in altitude.

```
class CMAltitudeData
```

## Overview

You do not create instances of this class directly. When you want to receive altimeter changes, create an instance of the [`CMAltimeter`](/documentation/CoreMotion/CMAltimeter) class and use that object to query for events or to start the delivery of events. The altimeter object creates new instances of this class at appropriate times and delivers them to the handler you specify.

## Topics

### Getting the Altitude Data

[`relativeAltitude`](/documentation/CoreMotion/CMAltitudeData/relativeAltitude)

The change in altitude (in meters) since the first reported event.

[`pressure`](/documentation/CoreMotion/CMAltitudeData/pressure)

The recorded pressure, in kilopascals.

## Relationships

### Conforms To

[`CVarArg`](/documentation/Swift/CVarArg)

[`NSCoding`](/documentation/Foundation/NSCoding)

[`NSSecureCoding`](/documentation/Foundation/NSSecureCoding)

[`CustomDebugStringConvertible`](/documentation/Swift/CustomDebugStringConvertible)

[`Hashable`](/documentation/Swift/Hashable)

[`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible)

[`Equatable`](/documentation/Swift/Equatable)

[`NSObjectProtocol`](/documentation/ObjectiveC/NSObjectProtocol)

[`NSCopying`](/documentation/Foundation/NSCopying)

### Inherits From

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

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)