VISPER-Redux

VISPER-Redux is an implementation of the redux-architecture in swift. It provides you with an app architecture to tackle the problem of distributed app state and state changes.

It is heavyly inspired by ReReactiveSwift and adds just some extensions to tackle composite app states and some integration features to use it in the VISPER-Application Framework.

If you want to learn more about redux, have a look at the following tutorials and documentations:

• A cartoon guide to Flux
• A cartoon Intro to Redux
• redux.js Documentation

State

VISPER-Redux stores the complete state of your app in a central struct to create a transparent representation of the current state of your different app components.

A typical composite app state for an app to manage your todos in the next week might look like that:

struct AppState {
    var userState : UserState
    var todoListState : TodoListState
    var imprintState : ImprintState
}

with some composite sub states:

struct UserState {
    var userName : String
    var isAuthenticated : Bool
}

struct TodoListState {
    var todos : [Todo]
}

struct ImprintState {
    var text : String
    var didAlreadyRead : Bool
}

Changing state

The current state in a VISPER-Redux app is stored in a central Store instance, which lives in a convinience wrapper object of type Redux. State change can only be achieved by dispatching an action (a simple message object) at the ActionDispatcher, and creating a modified new state in a reduce function.

A reduceFunction has the following form:

let reducer : (_ provider: ReducerProvider,_ action: ActionType, _ state: StateType) -> StateType

the reducer will be applied to all actions of type ActionType and to all states of type StateType. A reducer can be added to your redux architecture by adding it to the reducer container.

// add a reduce function
redux.reducerContainer.addReduceFunction(...)

// add a action reducer instance
redux.reducerContainer.addReducer(...)

An action is just an simple object conforming to the empty protocol Action, for example:

struct SetUsernameAction : Action{
    var newUsername : String
}

A short state change example

At first initialize an instance of type Redux

//initialize your starting app state here
let appState = ...
let redux = Redux(initialState: appState)

add a reducer (an object responsible for a state change) for your complete app state

let appReducer = { (reducerProvider: ReducerProvider, action: Action, currentState: AppState) -> AppState in
    return AppState(
        userState: reducerProvider.reduce(action,currentState.userState),
        todoListState: reducerProvider.reduce(action,currentState.todoListState),
        imprintState : reducerProvider.reduce(action,currentState.imprintState)
    )
}

redux.reducerContainer.addReduceFunction(appReducer)

add a specific reducer for changing your UserState

let setUsernameReducer = { (reducerProvider: ReducerProvider, action: SetUsernameAction, currentState: UserState) -> AppState in
    return UserState(userName: action.newUsername,
                     isAuthenticated: currentState.isAuthenticated)
}

redux.reducerContainer.addReduceFunction(appReducer)

create a SetUsernameAction

struct SetUsernameAction : Action{
    var newUsername : String
}

and dispatch it

let action = SetUsernameAction(newUsername: "Max Mustermann")
redux.actionDispatcher.dispatch(action)

your reducers will now be called and the setUsernameReducer will set the new UserStates property userName to "Max Mustermann"

You can prove that by:

assert(redux.store.observable.value.userState.userName == "Max Mustermann")

Observing state change

Observing state change ist simple. Just observe the observable property of your store:

redux.store.observable.subscribe { appState in
    print("New username is:\(appState.userState.userName)")                                   
}

VISPER-Redux contains a very simple implementation of Observable, with the name ObservableProperty, we recommend you to add some categories to it to use your favorite rx library with it.

Example

To run the example project, clone the repo, and run pod install from the Example directory first. It contains a typical counter Example app for demonstration purposes.

Installation

VISPER-Redux is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'VISPER-Redux'

Author

barteljan, jan.bartel@atino.net

License

VISPER-Redux is available under the MIT license. See the LICENSE file for more info.