Deleting item RxSwift MVVM pattern - ios

Hi have a tableview with sections and I am making API call to populate the tableView. I am also using the MVVm architecture. Now users are able to delete items but I try reloading the sections or tableView but nothing happens as the deleted item still remains in the tableView. Below is my code. Any help is appreciated
My ViewModel
Observable.zip(identiferElements, deviceElements).map {(identifers, devices, _) -> [MyInfoSection] in
var items: [MyInfoSection] = []
let identiferRepository = identifers.map({ (repository) -> MyInfoSectionItem in
let cellViewModel = IdentifiersCellViewModel(with: repository)
return MyInfoSectionItem.identifiersItem(viewModel: cellViewModel)
})
if identiferRepository.isNotEmpty {
items.append(MyInfoSection.setting(title: "Identifier", items: identiferRepository))
}
let deviceRepository = devices.map({ (repository) -> MyInfoSectionItem in
let cellViewModel = DevicesCellViewModel(with: repository)
return MyInfoSectionItem.devicesItem(viewModel: cellViewModel)
})
if deviceRepository.isNotEmpty {
items.append(MyInfoSection.setting(title: "Active Devices", items: deviceRepository))
}
return items
}.bind(to: elements).disposed(by: rx.disposeBag)
deletedEvent.drive(onNext: { (item) in
switch item {
case .identifiersItem(let viewModel):
identiferDeleted.onNext(viewModel.repository)
case .devicesItem(let viewModel):
deviceDeleted.onNext(viewModel.repository)
}
}).disposed(by: rx.disposeBag)
identiferDeleted.asObservable().flatMapLatest({ [weak self] (value) -> Observable<ResponseBase> in
log(value)
guard let self = self, let id = value.id else { return Observable.just(ResponseBase()) }
return self.provider.deleteAddress(id: id)
.trackActivity(self.loading)
.trackError(self.error)
}).subscribe(onNext: { (res) in
log(res)
}).disposed(by: rx.disposeBag)
ViewController
//viewDidLoad
let input = MyInfoViewModel.Input(trigger: refresh, segmentSelection: segmentSelected, selection: tableView.rx.modelSelected(MyInfoSectionItem.self).asDriver(), deleted: tableView.rx.modelDeleted(MyInfoSectionItem.self).asDriver())
let output = viewModel.transform(input: input)
More code would be added based on request. Thanks

Use combineLatest instead of zip. The user can only delete an item out of one section at a time and zip waits until both sections emit a new value before emitting. There might be other problems, but that is one for sure.
I would need to see compilable code for your view model to help further.

Related

How to clear datas on RxTableView

I'm stuck on RxCocoa problem.
I'm gonna implement clear tableView with Rx.
The app using MVVM with RxCocoa needs clear data for initializing tableView with infinite scroll.
But with binding tableView, I dunno how to clear it.
Thanks.
ViewController
self.viewModel.requestData() // request data to Server
self.viewModel.output.hotDealList
.scan(into: [ItemModel]()) { firstPosts, afterPosts in // For Infinite Scroll
return firstPosts.append(contentsOf: afterPosts)
}
.bind(to: self.tableView.rx.items(cellIdentifier: "itemCell", cellType: HotDealTableViewCell.self)) { [unowned self] (index, item, cell) in
self.setCellUI(item: item, cell: cell)
}.disposed(by: self.bag)
ViewModel
struct Output {
let hotDealList = BehaviorSubject<[ItemModel]>(value: [])
}
func requestData(page: String = "0") {
let _ = self.service.requestItemList(["page":page])
.subscribe(
onNext:{ response in
guard let serverModels = response.posts, !serverModels.isEmpty else {
return
}
self.output.hotDealList.onNext(serverModels)
}
).disposed(by: self.bag)
}
The solution here is to expand the state machine that you already have started. A Moore Machine (which is the easiest state machine to understand) consists of a number of inputs, a state, a start state, and a number of outputs. It is expressed in Rx using the scan operator and an Input enum.
You already have the scan operator setup, but you only have one input, hotDealList. You need to include a second input for clearing.
Something like this:
enum Input {
case append([ItemModel])
case clear
}
let state = Observable.merge(
viewModel.output.hotDealList.map { Input.append($0) },
viewModel.output.clear.map { Input.clear }
)
.scan(into: [ItemModel]()) { state, input in
switch input {
case let .append(page):
state.append(page)
case .clear:
state = []
}
}
In Rx, the outputs of the state machine are expressed by bindings. You already have one:
state.bind(to: self.tableView.rx.items(cellIdentifier: "itemCell", cellType: HotDealTableViewCell.self)) { [unowned self] (index, item, cell) in
self.setCellUI(item: item, cell: cell)
}
.disposed(by: bag)
If you need more, be sure to share your state observable.
BTW, using self inside the binder like that is a memory leak. I suggest you move the setCellUI(item:cell:) method into the HotDealTableViewCell class so you don't need self.

do(onNext:) called twice when table view row is selected

I'm facing a problem when selecting the table view row on RxSwift. For details, the code on the do(onNext:) function is called twice, thus lead to the navigation pushed twice too. Here is my code in the viewModel, please help me resolve it. Thanks so much.
struct Input {
let loadTrigger: Driver<String>
let searchTrigger: Driver<String>
let selectMealTrigger: Driver<IndexPath>
}
struct Output {
let mealList: Driver<[Meal]>
let selectedMeal: Driver<Meal>
}
func transform(_ input: HomeViewModel.Input) -> HomeViewModel.Output {
let popularMeals = input.loadTrigger
.flatMap { _ in
return self.useCase.getMealList()
.asDriver(onErrorJustReturn: [])
}
let mealSearchList = input.searchTrigger
.flatMap { text in
return self.useCase.getMealSearchList(mealName: text)
.asDriver(onErrorJustReturn: [])
}
let mealList = Observable.of(mealSearchList.asObservable(), popularMeals.asObservable()).merge().asDriver(onErrorJustReturn: [])
let selectedMeal = input.selectMealTrigger
.withLatestFrom(mealList) { $1[$0.row] }
.do(onNext: { meal in
self.navigator.toMealDetail(meal: meal)
})
return Output(mealList: mealList, selectedMeal: selectedMeal)
}
Edit: Here's the implemetation on the ViewController:
func bindViewModel() {
self.tableView.delegate = nil
self.tableView.dataSource = nil
let emptyTrigger = searchBar
.rx.text.orEmpty
.filter { $0.isEmpty }
.throttle(0.1, scheduler: MainScheduler.instance)
.asDriver(onErrorJustReturn: "")
let loadMealTrigger = Observable
.of(emptyTrigger.asObservable(), Observable.just(("")))
.merge()
.asDriver(onErrorJustReturn: "")
let searchTrigger = searchBar.rx.text.orEmpty.asDriver()
.distinctUntilChanged()
.filter {!$0.isEmpty }
.throttle(0.1)
let selectMealTrigger = tableView.rx.itemSelected.asDriver()
let input = HomeViewModel.Input(
loadTrigger: loadMealTrigger,
searchTrigger: searchTrigger,
selectMealTrigger: selectMealTrigger
)
let output = viewModel.transform(input)
output.mealList
.drive(tableView.rx.items(cellIdentifier: MealCell.cellIdentifier)) { index, meal, cell in
let mealCell = cell as! MealCell
mealCell.meal = meal
}
.disposed(by: bag)
output.selectedMeal
.drive()
.disposed(by: bag)
}
Firstly, is this RxSwift?
If so, the .do(onNext:) operator provides side effects when you receive a new event via a subscription; Therefore, two "reactions" will happen when a table row is tapped: 1. subscription method and 2. .do(onNext:) event. Unfortunately, I do not have any further insight into your code, so there may be other stuff creating that error aswell.
Good luck!

Tableview not receiving signals from Driver

I have the following MVVM-C + RxSwift code.
The problem is that the TableView is not receiving any signals. When I
debug the results I can see that the API call is returning what it should, the objects array is populated with objects but the tableview does not show any results. Here is the console output:
2018-11-13 16:12:08.107: searchText -> Event next(qwerty)
Search something: qwerty
2018-11-13 16:12:08.324: viewModel.data -> Event next([])
Could it be the tableview itself? Maybe wrong custom cell setup?
ViewController.swift:
tableView = UITableView(frame: self.view.frame)
tableView.delegate = nil
tableView.dataSource = nil
tableView.register(SearchResultCell.self, forCellReuseIdentifier: "SearchResultCell")
viewModel.data
.debug("viewModel.data", trimOutput: false)
.drive(tableView.rx.items(cellIdentifier: "SearchResultCell")) { row, object, cell in
cell.name.text = object.name
cell.something.text = object.something
}
.disposed(by: disposeBag)
ViewModel.swift:
let disposeBag = DisposeBag()
var searchText = BehaviorRelay(value: "something to search for")
lazy var data: Driver<[Object]> = {
return self.searchText.asObservable()
.debug("searchText", trimOutput: false)
.throttle(0.3, scheduler: MainScheduler.instance)
.distinctUntilChanged()
.flatMapLatest(searchSomething)
.asDriver(onErrorJustReturn: [])
}()
func searchSomething(query: String) -> Observable<[Object]> {
print("Search something: \(query)")
let provider = MoyaProvider<APIService>()
var objects = [Object]()
provider.rx.request(.search(query: query)).subscribe { event in
switch event {
case let .success(response):
do {
let responseJSON: NSDictionary = try (response.mapJSON() as? NSDictionary)!
objects = self.parse(json: responseJSON["results"] as Any)
} catch(let error) {
print(error)
}
break
case let .error(error):
print(error)
break
}
}
.disposed(by: disposeBag)
let result: Observable<[Object]> = Observable.from(optional: objects)
return result
}
When using flatMap, you do not want to create nested subscriptions. You will create an Observable that returns the expected result, and flatMap will take care of subscribing to it. In the current state of things, searchSomething will always return an empty array, as Observable.from(optional: objects) will be called before the request has a chance to complete.
Since version 10.0 of Moya, provider will cancel the requests it created when deallocated. Here, it will be deallocated when execution exits searchSomething, hence the network request won't have time to finish. Moving provider's declaration to the view model's level solves this issue.
Here's searchSomething(query: String) -> Observable<[Object]> rewritten.
let provider = MoyaProvider<APIService>()
func searchSomething(query: String) -> Observable<[Object]> {
print("Search something: \(query)")
return provider.rx.request(.search(query: query)).map { (response) -> [Object] in
let responseJSON: NSDictionary = try (response.mapJSON() as? NSDictionary)!
return self.parse(json: responseJSON["results"] as Any)
}
}
Instead of doing the transformation in subscribe, it's done in map, which will be called for every next event, being passed the value associated with the event.

RxSwift obtain value from one item in Observable sequence

I'm trying to gradually convert my App to RxSwift / MVVM. But I think I'm doing some things incorrectly.
In this example I have a static table with this specific information.
let itens = Observable.just([
MenuItem(name: GlobalStrings.menuItemHome, nameClass: "GPMainVC"),
MenuItem(name: GlobalStrings.menuItemProfile, nameClass: "GPMainVC"),
MenuItem(name: GlobalStrings.menuItemLevels, nameClass: "GPLevelsVC"),
])
I need to know the model(MenuItem) and the index when the user select a cell, but I am having trouble doing that
tableView.rx
.itemSelected
.map { [weak self] indexPath in
return (indexPath, self?.modelView.itens.elementAt(indexPath.row))
}
.subscribe(onNext: { [weak self] indexPath, model in
self?.tableView.reloadData()
//canĀ“t get MenuItem because model its a observable
//self?.didSelect((indexPath as NSIndexPath).row, name.nameClass)
})
.addDisposableTo(disposeBag)
Thanks in advance
You have to do next steps:
Use Variable. I think it's a better solution in your situation.
let itens = Variable([
MenuItem(name: GlobalStrings.menuItemHome, nameClass: "GPMainVC"),
MenuItem(name: GlobalStrings.menuItemProfile, nameClass: "GPMainVC"),
MenuItem(name: GlobalStrings.menuItemLevels, nameClass: "GPLevelsVC"),
])
Use the following code if you want to get index and model from a clicked cell.
tableView.rx
.itemSelected
.map { index in
return (index, self.items.value[index.row])
}
.subscribe(onNext: { [weak self] index, model in
// model is MenuItem class
})
.addDisposableTo(disposeBag)
I hope my answer was very helpful for you. Please let me know if you want more information about RxSwift opportunities in your task. Good luck!

RxSwift: code working only first time

I'm new in RxSwift. Some strange thing happens in my code.
I have a collection view and
Driver["String"]
Data for binding.
var items = fetchImages("flower")
items.asObservable().bindTo(self.collView.rx_itemsWithCellIdentifier("cell", cellType: ImageViewCell.self)) { (row, element, cell) in
cell.imageView.setURL(NSURL(string: element), placeholderImage: UIImage(named: ""))
}.addDisposableTo(self.disposeBag)
fetchImages
Function returns data
private func fetchImages(string:String) -> Driver<[String]> {
let searchData = Observable.just(string)
return searchData.observeOn(ConcurrentDispatchQueueScheduler(globalConcurrentQueueQOS: .Background))
.flatMap
{ text in // .Background thread, network request
return RxAlamofire
.requestJSON(.GET, "https://pixabay.com/api/?key=2557096-723b632d4f027a1a50018f846&q=\(text)&image_type=photo")
.debug()
.catchError { error in
print("aaaa")
return Observable.never()
}
}
.map { (response, json) -> [String] in // again back to .Background, map objects
var arr = [String]()
for i in 0 ..< json["hits"]!!.count {
arr.append(json["hits"]!![i]["previewURL"]!! as! String)
}
return arr
}
.observeOn(MainScheduler.instance) // switch to MainScheduler, UI updates
.doOnError({ (type) in
print(type)
})
.asDriver(onErrorJustReturn: []) // This also makes sure that we are on MainScheduler
}
Strange thing is this. First time when I fetch with "flower" it works and return data, but when I add this code
self.searchBar.rx_text.subscribeNext { text in
items = self.fetchImages(text)
}.addDisposableTo(self.disposeBag)
It doesn't work. It doesn't steps in flatmap callback, and because of this, doesn't return anything.
It works in your first use case, because you're actually using the returned Driver<[String]> via a bindTo():
var items = fetchImages("flower")
items.asObservable().bindTo(...
However, in your second use case, you aren't doing anything with the returned Driver<[String]> other than saving it to a variable, which you do nothing with.
items = self.fetchImages(text)
A Driver does nothing until you subscribe to it (or in your case bindTo).
EDIT: To make this clearer, here's how you could get your second use case to work (I've avoided cleaning up the implementation to keep it simple):
self.searchBar.rx_text
.flatMap { searchText in
return self.fetchImages(searchText)
}
.bindTo(self.collView.rx_itemsWithCellIdentifier("cell", cellType: ImageViewCell.self)) { (row, element, cell) in
cell.imageView.setURL(NSURL(string: element), placeholderImage: UIImage(named: ""))
}.addDisposableTo(self.disposeBag)

Resources