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# CHHapticDynamicParameter

A value that you send to a haptic pattern player to alter a property value during playback.

```
class CHHapticDynamicParameter
```

## Overview

Dynamic parameters change their associated event parameters at specific times. When you send a dynamic parameter to a haptic pattern player, the value associated with the parameter changes abruptly at the specified time, across all events in the pattern. To precipitate a gradual change, use a [`CHHapticParameterCurve`](/documentation/CoreHaptics/CHHapticParameterCurve) object.

For haptic intensity and audio volume, the final property value is equal to the original event parameter value multiplied by the dynamic parameter value. For all other parameters, the final property value is equal to the dynamic parameter value added to the original event parameter value. In both cases, the resulting value is limited to the range with minimum and maximum values corresponding to the specified event parameter.

## Topics

### Creating a Dynamic Parameter

[`init(parameterID:value:relativeTime:)`](/documentation/CoreHaptics/CHHapticDynamicParameter/init(parameterID:value:relativeTime:))

Creates a dynamic parameter from its ID, value, and start time.

[`CHHapticDynamicParameter.ID`](/documentation/CoreHaptics/CHHapticDynamicParameter/ID)

The identifier that reveals the type of property associated with a dynamic parameter.

### Specifying a Dynamic Parameter’s Value

[`parameterID`](/documentation/CoreHaptics/CHHapticDynamicParameter/parameterID)

The dynamic parameter ID defining the type of parameter being modified.

[`relativeTime`](/documentation/CoreHaptics/CHHapticDynamicParameter/relativeTime)

The time at which this dynamic parameter is applied, relative to the start time of the pattern.

[`value`](/documentation/CoreHaptics/CHHapticDynamicParameter/value)

The value of the dynamic parameter.


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