Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/sergdort/CleanArchitectureRxSwift

Example of Clean Architecture of iOS app using RxSwift
https://github.com/sergdort/CleanArchitectureRxSwift

architecture clean-architecture coredata ios mvvm reactive-programming realm rxswift

Last synced: about 1 month ago
JSON representation

Example of Clean Architecture of iOS app using RxSwift

Awesome Lists containing this project

README

        

# Clean architecture with [RxSwift](https://github.com/ReactiveX/RxSwift)

## Contributions are welcome and highly appreciated!!
You can do this by:

- opening an issue to discuss the current solution, ask a question, propose your solution etc. (also English is not my native language so if you think that something can be corrected please open a PR 😊)
- opening a PR if you want to fix bugs or improve something

### Installation

Dependencies in this project are provided via Cocoapods. Please install all dependecies with

`
pod install
`

> You can run this script `(exec_pod_install.sh)` in 'scripts' folder that help you install all dependecies

## High level overview
![](Architecture/Modules.png)

#### Domain

The `Domain` is basically what is your App about and what it can do (Entities, UseCase etc.) **It does not depend on UIKit or any persistence framework**, and it doesn't have implementations apart from entities

#### Platform

The `Platform` is a concrete implementation of the `Domain` in a specific platform like iOS. It does hide all implementation details. For example Database implementation whether it is CoreData, Realm, SQLite etc.

#### Application
`Application` is responsible for delivering information to the user and handling user input. It can be implemented with any delivery pattern e.g (MVVM, MVC, MVP). This is the place for your `UIView`s and `UIViewController`s. As you will see from the example app, `ViewControllers` are completely independent of the `Platform`. The only responsibility of a view controller is to "bind" the UI to the Domain to make things happen. In fact, in the current example we are using the same view controller for Realm and CoreData.

## Detail overview
![](Architecture/ModulesDetails.png)

To enforce modularity, `Domain`, `Platform` and `Application` are separate targets in the App, which allows us to take advantage of the `internal` access layer in Swift to prevent exposing of types that we don't want to expose.

#### Domain

Entities are implemented as Swift value types

```swift
public struct Post {
public let uid: String
public let createDate: Date
public let updateDate: Date
public let title: String
public let content: String
}
```

UseCases are protocols which do one specific thing:

```swift

public protocol PostsUseCase {
func posts() -> Observable<[Post]>
func save(post: Post) -> Observable
}

```

`UseCaseProvider` is a [service locator](https://en.wikipedia.org/wiki/Service_locator_pattern). In the current example, it helps to hide the concrete implementation of use cases.

#### Platform

In some cases, we can't use Swift structs for our domain objects because of DB framework requirements (e.g. CoreData, Realm).

```swift
final class CDPost: NSManagedObject {
@NSManaged public var uid: String?
@NSManaged public var title: String?
@NSManaged public var content: String?
@NSManaged public var createDate: NSDate?
@NSManaged public var updateDate: NSDate?
}

final class RMPost: Object {
dynamic var uid: String = ""
dynamic var createDate: NSDate = NSDate()
dynamic var updateDate: NSDate = NSDate()
dynamic var title: String = ""
dynamic var content: String = ""
}

```

The `Platform` also contains concrete implementations of your use cases, repositories or any services that are defined in the `Domain`.

```swift
final class PostsUseCase: Domain.PostsUseCase {

private let repository: AbstractRepository

init(repository: AbstractRepository) {
self.repository = repository
}

func posts() -> Observable<[Post]> {
return repository.query(sortDescriptors: [Post.CoreDataType.uid.descending()])
}

func save(post: Post) -> Observable {
return repository.save(entity: post)
}
}

final class Repository: AbstractRepository where T == T.CoreDataType.DomainType {
private let context: NSManagedObjectContext
private let scheduler: ContextScheduler

init(context: NSManagedObjectContext) {
self.context = context
self.scheduler = ContextScheduler(context: context)
}

override func query(with predicate: NSPredicate? = nil,
sortDescriptors: [NSSortDescriptor]? = nil) -> Observable<[T]> {
let request = T.CoreDataType.fetchRequest()
request.predicate = predicate
request.sortDescriptors = sortDescriptors
return context.rx.entities(fetchRequest: request)
.mapToDomain()
.subscribeOn(scheduler)
}

override func save(entity: T) -> Observable {
return entity.sync(in: context)
.mapToVoid()
.flatMapLatest(context.rx.save)
.subscribeOn(scheduler)
}
}
```

As you can see, concrete implementations are internal, because we don't want to expose our dependecies. The only thing that is exposed in the current example from the `Platform` is a concrete implementation of the `UseCaseProvider`.

```swift
public final class UseCaseProvider: Domain.UseCaseProvider {
private let coreDataStack = CoreDataStack()
private let postRepository: Repository

public init() {
postRepository = Repository(context: coreDataStack.context)
}

public func makePostsUseCase() -> Domain.PostsUseCase {
return PostsUseCase(repository: postRepository)
}
}
```

#### Application

In the current example, `Application` is implemented with the [MVVM](https://en.wikipedia.org/wiki/Model–view–viewmodel) pattern and heavy use of [RxSwift](https://github.com/ReactiveX/RxSwift), which makes binding very easy.

![](Architecture/MVVMPattern.png)

Where the `ViewModel` performs pure transformation of a user `Input` to the `Output`

```swift

protocol ViewModelType {
associatedtype Input
associatedtype Output

func transform(input: Input) -> Output
}
```

```swift
final class PostsViewModel: ViewModelType {
struct Input {
let trigger: Driver
let createPostTrigger: Driver
let selection: Driver
}
struct Output {
let fetching: Driver
let posts: Driver<[Post]>
let createPost: Driver
let selectedPost: Driver
let error: Driver
}

private let useCase: AllPostsUseCase
private let navigator: PostsNavigator

init(useCase: AllPostsUseCase, navigator: PostsNavigator) {
self.useCase = useCase
self.navigator = navigator
}

func transform(input: Input) -> Output {
......
}
```

A `ViewModel` can be injected into a `ViewController` via property injection or initializer. In the current example, this is done by `Navigator`.

```swift

protocol PostsNavigator {
func toCreatePost()
func toPost(_ post: Post)
func toPosts()
}

class DefaultPostsNavigator: PostsNavigator {
private let storyBoard: UIStoryboard
private let navigationController: UINavigationController
private let services: ServiceLocator

init(services: ServiceLocator,
navigationController: UINavigationController,
storyBoard: UIStoryboard) {
self.services = services
self.navigationController = navigationController
self.storyBoard = storyBoard
}

func toPosts() {
let vc = storyBoard.instantiateViewController(ofType: PostsViewController.self)
vc.viewModel = PostsViewModel(useCase: services.getAllPostsUseCase(),
navigator: self)
navigationController.pushViewController(vc, animated: true)
}
....
}

class PostsViewController: UIViewController {
private let disposeBag = DisposeBag()

var viewModel: PostsViewModel!

...
}
```

### Example

The example app is Post/TODOs app which uses `Realm`, `CoreData` and `Network` at the same time as a proof of concept that the `Application` level is not dependant on the Platform level implementation details.

| CoreData | Realm | Network |
| -------- | ----- | ------- |
|![](Architecture/CoreData.gif) | ![](Architecture/Realm.gif) | ![](Architecture/Network.gif) |

### Modularization

The corner stone of **Clean Architecture** is modularization, as you can hide implementation detail under `internal` access layer. Further read of this topic [here](https://github.com/microfeatures/guidelines)

### TODO:

* add tests
* add [MVP](https://en.wikipedia.org/wiki/Model–view–presenter) example
* [Redux](http://redux.js.org) example??

### Links
* [RxSwift](https://github.com/ReactiveX/RxSwift)
* [RxSwift Book](https://store.raywenderlich.com/products/rxswift)
* [Robert C Martin - Clean Architecture and Design](https://www.youtube.com/watch?v=Nsjsiz2A9mg)
* [Cycle.js](https://cycle.js.org)
* [ViewModel](https://medium.com/@SergDort/viewmodel-in-rxswift-world-13d39faa2cf5#.qse37r6jw) in Rx world

### Any questions?

* ping me on [Twitter](https://twitter.com/SergDort)