Reducer

public protocol Reducer

Protocol that represents a reducer

Example

struct MyReducer: Reducer {
  var initialState: Int = 1

  func reduce(state: Int, action: Action) -> Int? {

    // Cast the action to a specific action
    if let action = action as? SomeAction {
      // state changed, listeners will be notified
      return state + 1
    }

    // returning nil means the state did not change and listeners wont be notified
    return nil
  }
}

Note: Returning nil from reduce signifies that the state did not change which will not inform the listeners.

  • Inital state value for this particular reducer This initial state will be used to populate the Store state (which represents the app state)

    Declaration

    Swift

    var initialState: StateType
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  • stateKey Default implementation

    (Optional) The state key for this reducer. If not implemented (or set) the type of initialState will be used as a key.

    It is recommended to not set the stateKey as it will use the type name of the initialState instead.

    Default Implementation

    Undocumented

    Declaration

    Swift

    var stateKey: StateKey
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  • Generates a new state from the old state and an action

    Note: Returning nil from reduce signifies that the state did not change which will not inform the listeners

    Declaration

    Swift

    func reduce(state: StateType, action: Action) -> StateType?

    Parameters

    state

    the current state for this reducer type
    action

    the action dispatched to the store

    Return Value

    the new state

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