使用RxSwift和RxCocoa绑定模型并更新单元格

Question

I have a product$ which is Variable<[Product]>([]) and have a tableview with custom cell which has textfield. What I want is to update the cell when model change and when text of textfield change I want to update my model. Here what I did.

products$.asObservable()
        .bind(to: self.tableViewCal.rx.items(cellIdentifier: "edittingCell")){ (row, product: Product, cell: CaloriesEdittingCell) in
            cell.lblContentName.text = self.products$.value[row].name ?? ""
            cell.textValue.text = "\(self.products$.value[row].price ?? 0)"
            cell.textValue.rx.text
                .map({ value -> Float in
                    return (value! as NSString).floatValue
                })
                .subscribe({value in
                    self.products$.value[row].price = value.element
                    print(product)
                }).disposed(by: self.bag)
        }.disposed(by: bag)

Obviously, It will stuck in loop. So What I did is I created a another tempProduct$ with same datatype and assign the values of product$ to tempProduct$. Here is the code

tempProduct$.value = products$.value
tempProduct$.asObservable()
        .bind(to: self.tableViewCal.rx.items(cellIdentifier: "edittingCell")){ (row, product: Product, cell: CaloriesEdittingCell) in
            cell.lblContentName.text = self.products$.value[row].name ?? ""
            cell.textValue.text = "\(self.products$.value[row].price ?? 0)"
            cell.textValue.rx.text
                .map({ value -> Float in
                    return (value! as NSString).floatValue
                })
                .subscribe({value in
                    self.products$.value[row].price = value.element
                    print(product)
                }).disposed(by: self.bag)
        }.disposed(by: bag)

It works but If there is better solution then please let me know. Thanks in advance.

Answer 1

A better architectural choice for that sort of things is to adhere to unidirectional data flow principle. See https://redux.js.org/docs/basics/DataFlow.html for general intro. A possible implementation with RaspSwift would be like -

struct MyState: RaspState {
    var price: Float = 0.0

    mutating func apply(event: RaspEvent) {
        switch event {
        case let priceEvent as PriceEvent:
            self.price = priceEvent.price
        default:
        break
        }
    }
}

struct PriceEvent: RaspEvent {
    let price: Float
}

let myAggregator = RaspAggregator<MyState>(initial: MyState())

let priceSelector = RaspSelector<MyState, Float> { state -> Float in
    let value: Float = state.price
    return value
}

let price = myAggregator.select(selector: priceSelector)

price.bind(to: self.tableViewCal.rx.items(cellIdentifier: "edittingCell")){ (row, product: Product, cell: CaloriesEdittingCell) in
            cell.lblContentName.text = self.products$.value[row].name ?? ""
            cell.textValue.text = "\(self.products$.value[row].price ?? 0)"
            cell.textValue.rx.text
                .map({ value -> Float in
                    return (value! as NSString).floatValue
                })
                .subscribe({value in
                    myAggregator.manual(PriceEvent(price: value) as RaspEvent)
                    print(product)
                }).disposed(by: self.bag)
        }.disposed(by: bag)

Obviously, you can store a lot of other stuff in state object too, besides price.