ReSwift/public

Public channel for discussing ReSwift

nanocba

@nanocba

@nanocba Can you share an example viewModel(state:) factory method implementation? Am curious what you do there

That's on the presenter's side. Basically, a presenter always take some state and converts that into the view model that view needs. Note that the concept of view model is not that from MVVM. These are pure view models. They don't have any functions, just properties that map 1:1 to view properties. The type of things you see inside this viewModel(state:) method is always transformations from state to view model, such as if the state exposes a date and you need to display it in the view, this is the place where you format the Date into a String.

Christian Tietze

@DivineDominion

gotcha, thanks!

Tim DeGraw

@timdegraw_twitter

Can anyone shed some light on the state ReSwift? The last release was over a year ago so I'm curious if it is still being maintained.

Christian Tietze

@DivineDominion

I wanted to publish a Swift 5.x-built binary release for a while, guess I should put this onto my todo list for tomorrow for once :)

@timdegraw_twitter The lib works, is used in production, alive and kicking

Tim DeGraw

@timdegraw_twitter

Cool! Thank you. I'm working on a project that has it integrated and I was trying to decide whether to build on top of it or find an alternative. Thanks for letting me know. I'll keep my eye out for the update ;)

Christian Tietze

@DivineDominion

There're some large-scale changes in the pipeline that nobody ever got around to finish up that could make the approach look a bit more like modern Swift, but if you dig classic OOP for the subscribers, you'll be fine with the current state of the framework 👍

(And if you don't, it's easy to write closure-based convenience subscribers :))

Tim DeGraw

@timdegraw_twitter

Sounds great

I'm curious, is there built in support to persist to Realm/CoreData? Or do you projects usually serialize to disk?

Christian Tietze

@DivineDominion

ReSwift only comes with the state/subscriber/action/reducer flow, the rest is up to you

With CoreData, I usually represent the app's core in my own model objects and then serialize/deserialize them using CoreData. It goes against the framework grain a bit, because then you could just as well use a dumb SQLite DB, but I don't want to weave CoreData into every aspect of my app. It's pretty invasive when you follow most tutorials.

Tim DeGraw

@timdegraw_twitter

Interesting. I actually have written any apps that use CoreData. But I've used Realm quite a bit and I like it.

Our current implementation is really basic and it works great. The issue is that it doesn't persist to disk so I'm trying to figure out how to weave that in and also work the current flow using DI for testability.

nanocba

@nanocba

Anyone has play around with ReThunk and having them to return a promise? The idea is to be able to write code like
dispatch(thunk).then { // this closure is called once the promise in thunk is fulfilled }. That greatly helps increasing reusability of thunks IMHO.

Malcolm Jarvis

@mjarvis

@nanocba You can wrap the thunk creation in a function such as func foo(params) -> (Thunk, Promise), then use let (thunk, promise) = thunk(params); dispatch(thunk); promise.then { ... } -- This can be wrapped into helper functions and/or extensions on the base types such that you can do so without boilerplate, giving you what you're asking for.

(eg extension Store { func dispatch(_ thunkAndPromise: (Thunk, Promise)) -> Promise { ... })

Mycroft Canner

@mycroftcanner

How would you model state in a table view driven by an NSFetchResultsController?

I can let the NSFetchResultsControllerDelegateupdate the table view by inserting, updating, moving and deleting view and when the delegate methodcontrollerDidChangeContent(_:)is called, update the state using the fetch results controller's propertyfetchedObjects`.

If I use the FRC fetchedObjects and convert my entities to structs I will lose the benefits of faults (large objects can be represented by a fault instead, until they really are needed.) unless I just map fetchedObjects to their objectIDs and only keep the objectIDs in the state and create a state for a cell lazily when it is needed.

Malcolm Jarvis

@mjarvis

I probably would not mix NSFetchResultsController and ReSwift. I'd either get everything into ReSwift somehow (id references or otherwise), or I'd just use NSFetchResultsController directly.

Xiaoyu Guo

@MichaelGuoXY

Hi guys, anyone has any suggestions for this scenario? View A has a state StateA, View B has a state StateB, and both of them share some StateCommon, the question is what's the best practice here to dispatch an action to modify the StateCommon to be adopted by StateA and StateB which are respectively subscribed by View A and View B?

To be more clear:
View A subscribes StateA, View B subscribes StateB
How to let StateA and StateB share some common state? And if any changes happened to that common StateCommon, how to let StateA and StateB know? so that View A and View B would know as well.

Christian Tietze

@DivineDominion

@MichaelGuoXY E.g. instead of newState(_ state: StateB), subscribe to newState(_ state: ViewBState) with struct ViewBState { let stateB: StateB; let commonState: CommonState } (or use tuples)

Luciano Polit

@LucianoPolit

Hey everyone, I hope you are doing good. I would like to share with you a new framework that I have been working on in the last couple of months. It’s called Caesura and it’s powered by ReSwift.
Main features:

Modularization. It’s intended to be feature driven. It decouples your app into small independent modules. Your state will not grow in size any more.
Action driven navigation. It’s as flexible as UIKit is.
A different way to interact with your API than ReThunk. It’s easy to use and super testable.
Optional built-in modules: time traveling, crash detector and reporter, session injection, and more...

Please, visit the repository for more information and I strongly recommend you to try the example project to see what the framework is capable of.
Any suggestion is more than welcome, as well as your star ;)
Cheers!

Malcolm Jarvis

@mjarvis

@LucianoPolit Thanks for the information! I'll be sure to take a look.

Xiaoyu Guo

@MichaelGuoXY

Hey guys, it's me again :) Hope you are doing well. I've been using ReSwift for a year now and there is always some concern in my mind: is it really a good practice to keep all the states/substates in the memory?

Say I have a view, which dispatches an action to its middleware, the middleware talks to the network service and fetches the data back, after that it fires an action to set the data to its viewState, then the view observed its state changes and reflects that. Everything works perfect. But if I keep doing this for each modules in my app, will it keep increasing the memory usage and some day it might be too high?

I would like to know what are the todos and not-todos when dealing with various modules with various data (info displayed/stored in the state).

Malcolm Jarvis

@mjarvis

@MichaelGuoXY it is important to keep an eye on memory usage as you test & build your app. Continuously increasing your state can result in memory problems, yes.

Shawn Koh

@shawnkoh

hi all, does anyone know why attempting to dispatch a thunk (from ReSwift-Thunk) leads to recursive dispatch?

dispatching the fetchProjects thunk leads to a recursive dispatch and crashes the app.

Malcolm Jarvis

@mjarvis

@shawnkoh I don't see anything in that that would cause a recursive dispatch. Could you put together a small example project for us to try?

Shawn Koh

@shawnkoh

oh apologies i think i forgot to set equatable on the structs

haha

that feels like something that should be enforced by the compiler though, i wonder if store.subscriber's select function should require the struct to conform to Equatable

Malcolm Jarvis

@mjarvis

There is no requirement for equatable structs in state. ReSwift supports non-equatable state, it just can't do repeat skipping. Can you provide an example please?

Christian Tietze

@DivineDominion

Ran into a weird bug in my app that boiled down to a store subscriber caching a value, which didn't mix well with the order of store subscribers being informed of state updates. The general-purpose answer seems to be: put the cache info into the state, not into some service in the app. It's a super weird situation, though, because the cache was introduced to make NSTextView editing a bit less error prone. After all these years, I still wonder if I'm holding it wrong and if doing even more in the ReSwift stack would solve the problems.

hrln

@hrln

hi all! i'm new to this chat and ReSwift - but i've been eyeing it for years. first of all, thanks to the creators and maintainers for bringing this paradigm to native iOS! the ideas have changed the way i write apps

i'm amidst porting a side project to use ReSwift and am unsure how to resolve certain scenarios. what i'm grappling with right now is chaining asynchronous actions together

i have a LoadInitialStateAction that resolves with an array of [Item]; i have a middleware guarding for that action, and if it is .loaded(items), i dispatch(someThunk); someThunk being the next asynchronous action that relies on items. what i'm running into is the ReSwift:ConcurrentMutationStateError- Action has been dispatched while a previous action is being processed occurring when my someThunk returns quickly

i tried wrapping my main store and using a serial queue internally to dispatch, but that didnt work :worried: my fix was basically DispatchQueue.main.asyncAfter(.now() + 1) https://twitter.com/ios_memes/status/1159781903559528450/photo/1

this seems like a really common need, so i feel like i'm missing something - any advice welcome! (and i'll try to pay it forward with what i learn)

Christian Tietze

@DivineDominion

@hrln the error should only appear when you dispatch from multiple queues. Assuming you dispatch on the main queue by default, DispatchQueue.main.async without a delay should do the trick just as well since the main queue finishes one run loop run, which in your case would be the state mutation, before the next thing is processed.

Using 2 dispatch queues in your app is not a problem as long as you remember to return to main. It's a good practice to build components in a way that the caller doesn't notice if the queue/thread/... that work is done on is changed. So if you use a BG dispatch queue for networking, dispatch the result back on the main queue, and don't force callers to take care of that.

hrln

@hrln

appreciate the response @DivineDominion ! i did also try the main queue sans delay, but that didn't help :confounded:

in folks ReSwift setups, are there any techniques you tend to use involving queue management ?

Christian Tietze

@DivineDominion

when the app crashes, you should be able to inspect the stack trace in Xcode to see all active threads and where the culprit might be

e.g. recently we stumbled upon EKEventStore producing results on an Apple-internal, non-main queue to everyone's surprise

hrln

@hrln

thanks again @DivineDominion :slight_smile: ill dig into the stack trace

hrln

@hrln

i took your advice @DivineDominion, digging into the stack track and wrapping calls that completed on a background queue was the ticket :pray:

Christian Tietze

@DivineDominion

💪 great

Mehreen7

@Mehreen7

Hello everyone, i need to show a little text when my app just start, so im trying to add function into my reducer, into "case _ as ReSwiftInit:" but it dont work, can someone help me ? im new to ReSwift

Thank you

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