Automated tasks & transitioning UI between states about reactorkit

[zdnk]

Ok.

What I feel when looking at ReactorKit is that I am somehow missing the ViewModel. Reactor as by name already reminds of something that is yet behind the view model and controls all the tasks like networks requests/services etc.

[devxoul]

Global state management is not a ReactorKit's responsibility. So you can use anything to manage the synchronisation. For example, you can use a global Subject to store synchronisation process or you can even use Reactor as a global synchronisation state manager. The important thing is that every Reactor can observe the global state and update its state.

Let's assume that we have a sync state as a Variable.

SyncState.swift

struct SynchronisationState {
  var usernames: [String] // example properties that will be binded to table view
}
let syncState = Variable<SynchronisationState>(SynchronisationState(usernames: []))

AppDelegate.swift

func applicationDidBecomeActive(_ application: UIApplication) {
  Synchroniser.sync() { newState in
    syncState.value = newState // emit a synchronised state
  }
}

MyViewReactor.swift

class MyViewReactor: Reactor {
  enum Action { ... }
  enum Mutation {
    case setUsernames(String)
  }
  struct State {
    var usernames: [String]
  }

  // Merges two observables into a single observabe:
  //   1. Mutation observable from Reactor
  //   2. Mutation observable from global `syncState`
  func transform(mutation: Observable<Mutation>) -> Observable<Mutation> {
    let fromSyncState = syncState.asObservable()
      .map { $0.usernames }
      .map { Mutation.setUsernames($0) }
    return Observable.merge(mutation, fromSyncState)
  }

  func reduce(state: State, mutation: Mutation) -> State {
    switch mutation {
    case let .setUsernames(usernames):
      var newState = state
      newState.usernames = usernames
      return newState
    }
  }
}

[zdnk]

I see. So I should also transform and map the data as they are supposed to go to view? Does Reactor also poses as ViewModel then?

What about transitioning between data? Like UITableViews beginUpdate, insertRows etc?

[devxoul]

@zdenektopic, You can directly map the global state to the View but it's recommended to use Reactor for testability. It's true that a Reactor it similar to a ViewModel because ReactorKit was originally started from MVVM.

If you're using RxDataSources you just can use RxTableViewSectionedAnimatedDataSource or RxCollectionViewSectionedAnimatedDataSource for animated updates. Otherwise you can use beginUpdate() and endUpdate().

[devxoul]

Please reopen it if you have further questions :)