Only one switch is on - ios

Question

I'm struggle with following challenge. I created table view with custom cell that contains switch. I wanna only one switch can be on i.e, for instance after launch I switched on 3rd switched and then I switched on 7th switch and thus the 3rd one is switched off and so on. I use rx + protocols for cell and don't understand all the way how to determine which switch was toggled. Previously I was going to use filter or map to look up in dataSource array which switch is on and somehow handle this, but now I messed up with it. I'm not sure it's possible without using table view delegate methods. Thanks a lot, hope someone could explain where I am wrong.
//My cell looks like this:
// CellViewModel implementation
import Foundation
import RxSwift
protocol ViewModelProtocol {
var bag:DisposeBag {get set}
func dispose()
}
class ViewModel:ViewModelProtocol {
var bag = DisposeBag()
func dispose() {
self.bag = DisposeBag()
}
}
protocol CellViewModelProtocol:ViewModelProtocol {
var isSwitchOn:BehaviorSubject<Bool> {get set}
}
class CellVM:ViewModel, CellViewModelProtocol {
var isSwitchOn: BehaviorSubject<BooleanLiteralType> = BehaviorSubject(value: false)
let internalBag = DisposeBag()
override init() {
}
}
//My Cell implementation
import UIKit
import RxSwift
import RxCocoa
class Cell:UITableViewCell {
static let identifier = "cell"
#IBOutlet weak var stateSwitch:UISwitch!
var vm:CellViewModelProtocol? {
didSet {
oldValue?.dispose()
self.bindUI()
}
}
var currentTag:Int?
var bag = DisposeBag()
override func awakeFromNib() {
super.awakeFromNib()
self.bindUI()
}
override func prepareForReuse() {
super.prepareForReuse()
self.bag = DisposeBag()
}
private func bindUI() {
guard let vm = self.vm else { return }
self.stateSwitch.rx.controlEvent(.valueChanged).withLatestFrom(self.stateSwitch.rx.value).observeOn(MainScheduler.asyncInstance).bind(to: vm.isSwitchOn).disposed(by: vm.bag)
}
}
//TableViewController implementation
import UIKit
import RxSwift
import RxCocoa
class TableViewController: UITableViewController {
private var dataSource:[CellViewModelProtocol] = []
var vm = TableViewControllerVM()
override func viewDidLoad() {
super.viewDidLoad()
self.tableView.estimatedRowHeight = 70
self.tableView.rowHeight = UITableView.automaticDimension
self.bindUI()
}
private func bindUI() {
vm.dataSource.observeOn(MainScheduler.asyncInstance).bind { [weak self] (dataSource) in
self?.dataSource = dataSource
self?.tableView.reloadData()
}.disposed(by: vm.bag)
}
// MARK: - Table view data source
override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.dataSource.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: Cell.identifier, for: indexPath) as! Cell
if cell.vm == nil {
cell.vm = CellVM()
}
return cell
}
}
class TableViewControllerVM:ViewModel {
var dataSource:BehaviorSubject<[CellViewModelProtocol]> = BehaviorSubject(value: [])
let internalBag = DisposeBag()
override init() {
super.init()
dataSource.onNext(createDataSourceOf(size: 7))
self.handleState()
}
private func createDataSourceOf(size:Int) -> [CellViewModelProtocol] {
var arr:[CellViewModelProtocol] = []
for _ in 0..<size {
let cell = CellVM()
arr.append(cell)
}
return arr
}
private func handleState() {
}
}

Answer 1

Maybe this code will help you:
extension TableViewController {
// called from viewDidLoad
func bind() {
let cells = (0..<7).map { _ in UUID() } // each cell needs an ID
let active = ReplaySubject<UUID>.create(bufferSize: 1) // tracks which is the currently active cell by ID
Observable.just(cells) // wrap the array in an Observable
.bind(to: tableView.rx.items(cellIdentifier: "Cell", cellType: Cell.self)) { _, element, cell in
// this subscription causes the inactive cells to turn off
active
.map { $0 == element }
.bind(to: cell.toggleSwitch.rx.isOn)
.disposed(by: cell.disposeBag)
// this subscription watches for when a cell is set to on.
cell.toggleSwitch.rx.isOn
.filter { $0 }
.map { _ in element }
.bind(to: active)
.disposed(by: cell.disposeBag)
}
.disposed(by: disposeBag)
}
}

Answer 2

Have a similar UI,so tested locally and it works.But not very neat code.
ProfileCellViewModel
struct ProfileCellViewModel {
// IMPORTANT!!!
var bibindRelay: BehaviorRelay<Bool>?
}
ProfileCell
final class ProfileCell: TableViewCell {
#IBOutlet weak var topLabel: Label!
#IBOutlet weak var centerLabel: Label!
#IBOutlet weak var bottomLabel: Label!
#IBOutlet weak var onSwitch: Switch!
public var vm: ProfileCellViewModel? {
didSet {
// IMPORTANT!!!
if let behaviorRelay = vm?.bibindRelay {
(onSwitch.rx.controlProperty(editingEvents: .valueChanged,
getter: { $0.isOn }) { $0.isOn = $1 } <-> behaviorRelay)
.disposed(by: self.rx.reuseBag)
}
}
}
}
ProfileViewModel
final class ProfileViewModel: ViewModel, ViewModelType {
struct Input {
let loadUserProfileStarted: BehaviorRelay<Void>
}
struct Output {
let userItems: BehaviorRelay<[ProfileCellViewModel]>
let chatRelay: BehaviorRelay<Bool>
let callRelay: BehaviorRelay<Bool>
}
let input = Input(loadUserProfileStarted: BehaviorRelay<Void>(value: ()))
let output = Output(userItems: BehaviorRelay<[ProfileCellViewModel]>(value: []),
chatRelay: BehaviorRelay<Bool>(value: false),
callRelay: BehaviorRelay<Bool>(value:false))
override init() {
super.init()
// IMPORTANT!!!
Observable.combineLatest(output.chatRelay,output.callRelay).pairwise().map { (arg0) -> Int in
let (pre, curr) = arg0
let preFlag = [pre.0,pre.1].filter { $0 == true }.count == 1
let currFlag = [curr.0,curr.1].filter { $0 == true }.count == 2
if preFlag && currFlag {
return [pre.0,pre.1].firstIndex(of: true) ?? 0
}
return -1
}.filter {$0 >= 0}.subscribe(onNext: { (value) in
[self.output.chatRelay,self.output.callRelay][value].accept(false)
}).disposed(by: disposeBag)
}
private func createProfileCellItems(user: User) -> [ProfileCellViewModel] {
// IMPORTANT!!!
let chatCellViewModel = ProfileCellViewModel(topText: nil,
centerText: R.string.i18n.chat(),
bottomText: nil,
switchStatus: true,
bibindRelay: output.chatRelay)
// IMPORTANT!!!
let callCellViewModel = ProfileCellViewModel(topText: nil,
centerText: R.string.i18n.call(),
bottomText: nil,
switchStatus: true,
bibindRelay: output.callRelay)
return [roleCellViewModel,
teamCellViewModel,
statusCellViewModel,
sinceCellViewModel,
chatCellViewModel,
callCellViewModel]
}
}
I mark the codes you should pay attention to with // IMPORTANT!!!