public protocol ConditionalFeature : ConditionalFeatureDefinition

Features that are not guaranteed to be available all the time must conform to this protocol.

You implement a conditional feature like so:

public class TimelineFeature: ConditionalFeature {
    /// Set the availability to .purchasRequired, .runtimeEvaluated or .userToggled as appropriate
    public static var availability: FeatureAvailability = .runtimeEvaluated

    public static var description: String = "Maintains an in-memory timeline of actions for debugging and reporting"

    /// If availability is `runtimeEvaluated`, you must make `isAvailable` return whether or not it is available.
    /// Otherwise do not define a property for it and the `DefaultAvailabilityChecker` will be used to work out
    /// the correct value of this by calling into the `UserDefaultsFeatureToggles` or `PurchaseValidator`.
    public static var isAvailable: Bool? = true

    /// If using `runtimeEvaluated` you can use this function to set `isAvailable` at startup based on
    /// some other condition. Beware of dependency on other features and non-determinate initialising sequence.
    public static func prepare(actions: FeatureActionsBuilder) {
        if isAvailable == true {
            // Tracks the user's history of actions performed
            Flint.dispatcher.add(observer: TimelineDispatchObserver.instance)

Apps must call request to test if the action is available, and then call perform with the resulting request instance.

  • request(_:) Default implementation

    Call to request invocation of the conditionally available action.

  • return: nil if the action’s feature is not available, or a request instance that can be used to perform the action directly or on a specific ActionSession if the feature is available

  • Note

    This is defined in the protocol so you may override it if you have other ways to validate features.

    Default Implementation

    Verifies that the feature is correctly prepared in Flint and tests isAvailable to see if it is true. If so, returns a request that can be used to perform the action, otherwise nil.

    The default isAvailable implementation will delegate to the AvailabilityChecker to see if the feature is available.



    static func request<ActionType>(_ actionBinding: ConditionalActionBinding<Self, ActionType>) -> VerifiedActionBinding<Self, ActionType>? where ActionType : Action
  • action(_:) Extension method

    Function for binding a conditional feature and action pair, to restrict how this can be done externally by app code.


    This exists only in an extension as it is not an extension point for features to override.



    static func action<ActionType>(_ action: ActionType.Type) -> ConditionalActionBinding<Self, ActionType> where ActionType : Action