Should viewModel import framework that exposes UIKit like RxCocoa? Maybe it's better to expose input/output as Observable's and convert them to Driver in viewController implementation where it's legit to import RxCocoa?

Hi, I have a question related to architecture of view model.

Let's assume that I have a requirement to store network requests payload in Realm in order to be able to access data even if the user is offline. Currently in the example you show how to use Network or Realm or CoreData but not all together.

If i want to fulfill the requirement I need to do the following:

1. Pass 2 use cases into my view model . One is the network use case and the other one is the realm use case
2. Execute a call to the server via the Network use case and then use flat map to get the results and store them in Realm.
3. If the user is offline i can simply fetch the data from realm use case instead of the network use case.

I think it can work but maybe there is a better way to achieve it. Maybe by creating an abstraction layer on top of it that will do the call (either to the server or to the offline database in case the user is online/offline)

What do you think ?

Thanks!

Hi, I started to work on some side project which is based on this great project.

I facing some strange issue that when i execute a request from my view model to the server if the request failed the app crash. After debug it i found the crash is because the asserationFailure command check the error and because the error object is not nil the app crash.

This is the whole function:

func asDriverOnErrorJustComplete() -> Driver<E> { return asDriver { error in assertionFailure("Error \(error)") return Driver.empty() } }

My view model code is:

` let login = input.loginTrigger.withLatestFrom(emailAndPassword) .flatMapLatest({ [unowned self] (email, password) in

        return self.loginUseCase.login(username: email, password: password)
            .trackActivity(activityIndicator)
            .trackError(errorTracker)
            .asDriverOnErrorJustComplete()
    })

`

As you can see i use the same best practices like you use in your project. I also tried to change your code so network requests will fail and the asDriverOnErrorJustComplete but from some reason on your project it ignore the asserationFailure line. Can someone advice what should i do or what i am doing wrong?

thanks!

Hello,

in Postentry the part where Encodable do the task to decode json from internet. Is there any efficient and fast way to do this? like say you have nested object in one you gotta have several lines of code just to decode it. Thank you.

final class Repository<T: CoreDataRepresentable>: AbstractRepository where T == T.CoreDataType.DomainType

could not understand how T.CoreDataType.DomainType is returning back the Domain Type .

In case of Domain.Post, Post is conforming to CoreDataRepresentable `extension Post: CoreDataRepresentable { typealias CoreDataType = CDPost ....

}`

and CDPost conforms to DomainConvertibleType and Persistable But nowhere associatedtype DomainType is defined.

Can you please clarify?

Hello All I'm new to Clean Architecture, for the last couple of days, I've been struggling with learning the basic concepts of Clean Architecture, For iOS, I have 2 main sources for learning, This repo & Raymond's implementation here. These 2 implementations differ in the concepts of clean architecture. 1- one example is that this implementation relies on a Domain target to store all the models for the app, All the targets that want to use one of these models has to import Domain to see them. 2- Another example is that Raymond's implementation relies on workers to do the actual work of the interactor, why doesn't this repo make use of these workers to push the Single Responsibility Principle further?

Any help is highly appreciated!

Hi Guys, I'm very exited with this architecture and want to thank you. While working with it I've got some questions. Could you please provide an example for the following case: I have a cell with a textfield placed on it. How should I create an Input for controller's ViewModel in this case to make it work properly with cells reusability?

Thanks.

Hi guys,

first of all, let me thank you for your work, which is really great and inspiring! I've been using MVVM in iOS since 4 years now and I've learned that everyone has its personal way to implement things with this pattern and, most of all, everyone intend a "View Model" in different way. However, there seems to be 2 things that almost everyone agrees upon:

1. Views should NEVER know the existence of the "model layer"
2. In terms of separations between layers, UIViews and UIViewControllers falls inside the "View" layer

Taking a look at your example, in the PostsViewController, you're fetching the UITableView with the .rx extension: inside the closure, you're directly referencing the UITableViewCells IBOutlets and directly populating with model properties, which (in my opinion) totally breaks the MVVM pattern for different reasons :

• The UITableViewCell (a view) is fully aware (and directly accessing) something from the Model layer.
• The cell is configured by a single view controller, meaning that the same cell must be configured in every scenario it's going to be used (suppose you have another screen where you would like to present
• There's no "cell view Model" concept, which could be useful to reuse the same cell (with same outlets) to display data from different models.

Does it make sense to you? Am I being too "strict to the pattern" for your scenario? Thanks in advance :)

Hi,

As I mentioned in the title, what is the difference between two use cases? observeOn: https://github.com/sergdort/CleanArchitectureRxSwift/blob/master/Network/Network/Network.swift subscribeOn: https://github.com/sergdort/CleanArchitectureRxSwift/blob/master/RealmPlatform/Repository/Repository.swift

Thank you. Your example is very great and it helps me a lot :)

Let's say we want to save PostDetail model also in this PostsUseCase, in that case, how do we satisfy the generic constraint for it.

final class PostsUseCase<Repository>: Domain.PostsUseCase where Repository: AbstractRepository, Repository.T == Post {

    private let repository: Repository

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

     func save(postDetail: PostDetail) -> Observable<Void> {
        return repository.save(entity: postDetail)
    }

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

}

As the title says, I have got two questions trying to figure out why it's required or what's the underlying thinking around it.

1, Why do you use do in ViewModel instead of using subscribe in ViewModel?

        let dismiss = Driver.of(save, input.cancelTrigger)
        .merge()
        .do(onNext: navigator.toPosts)

Is there a specific reason to use do here? I remember that I read somewhere about do is a bad practice since it's a side effect, why not just use subscribe to achieve the pretty much same thing?

2, I know Driver has bunch of benefit, a) main thread b) no error c) shared

    struct Input {
        let cancelTrigger: Driver<Void>
        let saveTrigger: Driver<Void>
        let title: Driver<String>
        let details: Driver<String>
    }
    struct Output {
        let dismiss: Driver<Void>
        let saveEnabled: Driver<Bool>
    }

But over here it makes sense to use it for Output, but why we are using it for input?

As far as I know, rxSwift is 3rd party library. If the use case which is main logic of the app containing 3rd party library.. at the base of the app it's depending on rxSwift.

Meaning that this one is violated clean architecture at the very base. You can't copy paste the use case and domain without rxSwift library.

And this project lack of unit test as well, unit test is the interface of the domain.

Hi. I found this good repo today, and learn so much from it. But I maybe just found a memory leak. Select the "Network" tab, and select one post what ever you like, then the edit post vc come in, then click the back button, edit post vc out. Now, check the memory graph in Xcode, the edit post vc instance can't be released. I check the code and don't know why.

I think memory leak is a difficult thing in software develop work, especially when using RxSwift. Hope you can correct this.

HI, First to say, this an awesome project which focus on Clean Architecture and my main reference. Now i am on a Combine project and requires ActivityIndicator and ErrorTracker on Combine Version.

Hi! Thanks for providing a really nice starting point to think about how to build up an app and separate concerns. Of course, my first improvement was to have a UsecaseProviding and UsecaseDefinable protocol.

public protocol UsecaseProviding {
    associatedtype Usecase: UsecaseDefinable

    func makeUsecase() -> Usecase
}

public protocol UsecaseDefinable {
    associatedtype DomainEntity

    func entities() -> Observable<[DomainEntity]>
    func save(entity: DomainEntity) -> Observable<Void>
    func delete(entity: DomainEntity) -> Observable<Void>
}

However, as soon as I begin the implementation in the Database target, for example:

public final class PostsUsecaseProvider: UsecaseProviding {
    public typealias Usecase = PostsUsecase<Repository<Post>>
}

I'll get an error like: type alias cannot be declared public, because its underlying type uses an internal type because the Repository types are all internal. As they should be. That's specific logic for the database. However, I do want to have a concrete implementation of the Usecase and UsecaseProvider in the Database target.

The easiest fix would be to just publicize the Repository parts, but that feels kind of dirty. How would you fix this?

PostsViewModel is exposing to the view the Post mode as output: let selectedPost: Driver<Post>

My question is: PostsViewController knows Post data model which means that the view knows the model. As far as I understand MVVM architecture the UI (view) doesn't need to know the model (Post).

What do you think? is there a place to change the selectedPost parameter to be: let selectedPost: Driver<PostViewModel> ?

I tried Xcode 10, it works fine, but crashes on Xcode 11 whenever you click Realm Tab.

RunLoopThreadScheduler:

private final class ThreadTarget: NSObject { @objc fileprivate func threadEntryPoint() { let runLoop = RunLoop.current ***CRASH: com.CleanArchitectureRxSwift.RealmPlatform.Repository (8): signal SIGABRT runLoop.add(NSMachPort(), forMode: RunLoop.Mode.default) runLoop.run() } }

2019-09-24 22:40:34.205345+1200 CleanArchitectureRxSwift[95204:325374] *** Terminating app due to uncaught exception 'RLMException', reason: 'Primary key property 'uid' does not exist on object 'RMPhoto''