# decayTime The time at which a haptic pattern’s intensity begins decreasing. ``` static let decayTime: CHHapticEvent.ParameterID ``` ## Discussion This parameter can be an event parameter or a dynamic parameter. A fixed value indicates that the haptic begins decreasing in intensity at the set time, where time `0` indicates now, or the current time. A dynamic value indicates that the start time of the decrease can change. For example, a value of `0` indicates that the decay time is at its default value. Positive values up to `1.0` increase the decay time exponentially, while negative values down to `-1.0` decrease the decay time exponentially. Haptic intensity responds to this parameter. For example, the following graphic shows the intensity of a haptic pattern in gray. At the beginning, the haptic pattern’s intensity increases from zero to its final value over a certain amount of time; this duration is called the *attack*. As the haptic pattern reaches its end, the intensity gradually transitions to zero over a certain amount of time; this duration is called the *decay*.  --- Copyright © 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)