# HMMutableCharacteristicEvent A mutable event that is evaluated based on the value of a characteristic. ``` class HMMutableCharacteristicEvent where TriggerValueType : NSCopying ``` ## Topics ### Configuring the event [`var characteristic: HMCharacteristic`](/documentation/HomeKit/HMMutableCharacteristicEvent/characteristic) The characteristic associated with the event. [`var triggerValue: TriggerValueType?`](/documentation/HomeKit/HMMutableCharacteristicEvent/triggerValue) The value of the characteristic that triggers the event. ## Relationships ### Inherits From [`HMCharacteristicEvent`](/documentation/HomeKit/HMCharacteristicEvent) ### Conforms To [`CustomDebugStringConvertible`](/documentation/Swift/CustomDebugStringConvertible) [`SendableMetatype`](/documentation/Swift/SendableMetatype) [`CustomStringConvertible`](/documentation/Swift/CustomStringConvertible) [`Equatable`](/documentation/Swift/Equatable) [`NSCopying`](/documentation/Foundation/NSCopying) [`NSObjectProtocol`](/documentation/ObjectiveC/NSObjectProtocol) [`NSMutableCopying`](/documentation/Foundation/NSMutableCopying) [`Sendable`](/documentation/Swift/Sendable) [`CVarArg`](/documentation/Swift/CVarArg) [`Hashable`](/documentation/Swift/Hashable) --- 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)