---
title: PHASEEnvelopeSegment
framework: phase
role: symbol
role_heading: Class
path: phase/phaseenvelopesegment
---

# PHASEEnvelopeSegment

A curved portion of an envelope.

## Declaration

```swift
class PHASEEnvelopeSegment
```

## Overview

Overview This class specifies a curve that determines the _y-_value rate of change over a particular portion of an envelope’s graph. For example, the difference between a PHASECurveType.cubed segment and an PHASECurveType.inverseCubed segment is that they share opposite rates of change; where the cubed curve’s y value changes fastest in the segment’s domain, the inverse-cubed curve changes slowest, and vice versa.

## Topics

### Creating a Segment

- [init(endPoint:curveType:)](phase/phaseenvelopesegment/init(endpoint:curvetype:).md)

### Shaping a Segment

- [curveType](phase/phaseenvelopesegment/curvetype.md)
- [endPoint](phase/phaseenvelopesegment/endpoint.md)

## Relationships

### Inherits From

- [NSObject](objectivec/nsobject-swift.class.md)

### Conforms To

- [CVarArg](swift/cvararg.md)
- [CustomDebugStringConvertible](swift/customdebugstringconvertible.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [NSObjectProtocol](objectivec/nsobjectprotocol.md)

## See Also

### Dynamic Sound Control

- [PHASEEnvelope](phase/phaseenvelope.md)
- [PHASECurveType](phase/phasecurvetype.md)
- [PHASENumericPair](phase/phasenumericpair.md)
- [Playback Parameterization](phase/playback-parameterization.md)