CancellableValueChangedEventArgs

public class CancellableValueChangedEventArgs<T>

An event argument set for an event that tracks changes to a property, while exposing a cancel that can be changed by clients to cancel the state change

  • A copy of the old value that was changed.

    Declaration

    Swift

    public let oldValue: T

  • A copy of the new value that is being changed into.

    Declaration

    Swift

    public let newValue: T

  • Variable that event handlers can use to mark this change event as ‘canceled’.

    The semantics of a canceled value change event are handled by the event publisher, but is usually implied to cancel the change of the associated state to newValue.

    Multiple event listeners may toggle this value on and off as they take turns handling the event that this argument object accompanies, but only the last value cancel was attributed to is seen by event publishers upstream.

    Declaration

    Swift

    public var cancel: Bool

  • Undocumented

    Declaration

    Swift

    public init(oldValue: T, newValue: T)