Awesome
RxFeedback
The simplest architecture for RxSwift
<img src="https://github.com/kzaher/rxswiftcontent/raw/master/RxFeedback.png" width="502px" /> typealias Feedback<State, Event> = (Observable<State>) -> Observable<Event>
public static func system<State, Event>(
initialState: State,
reduce: @escaping (State, Event) -> State,
feedback: Feedback<State, Event>...
) -> Observable<State>
Why
-
Straightforward
- If it did happen -> Event
- If it should happen -> Request
- To fulfill Request -> Feedback loop
-
Declarative
- System behavior is first declaratively specified and effects begin after subscribe is called => Compile time proof there are no "unhandled states"
-
Debugging is easier
- A lot of logic is just normal pure function that can be debugged using Xcode debugger, or just printing the commands.
-
Can be applied on any level
- Entire system
- application (state is stored inside a database, CoreData, Firebase, Realm)
- view controller (state is stored inside
system
operator) - inside feedback loop (another
system
operator inside feedback loop)
-
Works awesome with dependency injection
-
Testing
- Reducer is a pure function, just call it and assert results
- In case effects are being tested -> TestScheduler
-
Can model circular dependencies
-
Completely separates business logic from effects (Rx).
- Business logic can be transpiled between platforms (ShiftJS, C++, J2ObjC)
Examples
Simple UI Feedback loop
Observable.system(
initialState: 0,
reduce: { (state, event) -> State in
switch event {
case .increment:
return state + 1
case .decrement:
return state - 1
}
},
scheduler: MainScheduler.instance,
feedback:
// UI is user feedback
bind(self) { me, state -> Bindings<Event> in
let subscriptions = [
state.map(String.init).bind(to: me.label.rx.text)
]
let events = [
me.plus.rx.tap.map { Event.increment },
me.minus.rx.tap.map { Event.decrement }
]
return Bindings(
subscriptions: subscriptions,
events: events
)
}
)
<img src="https://github.com/kzaher/rxswiftcontent/raw/master/Counter.gif" width="320px" />
Play Catch
Simple automatic feedback loop.
Observable.system(
initialState: State.humanHasIt,
reduce: { (state: State, event: Event) -> State in
switch event {
case .throwToMachine:
return .machineHasIt
case .throwToHuman:
return .humanHasIt
}
},
scheduler: MainScheduler.instance,
feedback:
// UI is human feedback
bindUI,
// NoUI, machine feedback
react(request: { $0.machinePitching }, effects: { (_) -> Observable<Event> in
return Observable<Int>
.timer(1.0, scheduler: MainScheduler.instance)
.map { _ in Event.throwToHuman }
})
)
<img src="https://github.com/kzaher/rxswiftcontent/raw/master/PlayCatch.gif" width="320px" />
Paging
Driver.system(
initialState: State.empty,
reduce: State.reduce,
feedback:
// UI, user feedback
bindUI,
// NoUI, automatic feedback
react(request: { $0.loadNextPage }, effects: { resource in
return URLSession.shared.loadRepositories(resource: resource)
.asSignal(onErrorJustReturn: .failure(.offline))
.map(Event.response)
})
)
Run RxFeedback.xcodeproj
> Example
to find out more.
Installation
CocoaPods
CocoaPods is a dependency manager for Cocoa projects. You can install it with the following command:
$ gem install cocoapods
To integrate RxFeedback into your Xcode project using CocoaPods, specify it in your Podfile
:
pod 'RxFeedback', '~> 3.0'
Then, run the following command:
$ pod install
Carthage
Carthage is a decentralized dependency manager that builds your dependencies and provides you with binary frameworks.
You can install Carthage with Homebrew using the following command:
$ brew update
$ brew install carthage
To integrate RxFeedback into your Xcode project using Carthage, specify it in your Cartfile
:
github "NoTests/RxFeedback" ~> 3.0
Run carthage update
to build the framework and drag the built RxFeedback.framework
into your Xcode project. As RxFeedback
depends on RxSwift
and RxCocoa
you need to drag the RxSwift.framework
and RxCocoa.framework
into your Xcode project as well.
Swift Package Manager
The Swift Package Manager is a tool for automating the distribution of Swift code and is integrated into the swift
compiler.
Once you have your Swift package set up, adding RxFeedback as a dependency is as easy as adding it to the dependencies
value of your Package.swift
.
dependencies: [
.package(url: "https://github.com/NoTests/RxFeedback.swift.git", majorVersion: 1)
]
Difference from other architectures
- Elm - pretty close, feedback loops for effects instead of
Cmd
, which effects to perform are encoded into state and queried by feedback loops - Redux - kind of like this, but feedback loops instead of middleware
- Redux-Observable - observables observe state vs. being inside middleware between view and state
- Cycle.js - no simple explanation :), ask @andrestaltz
- MVVM - separates state from effects and doesn't require a view