RxSwift Observe changes on model and Make request - swift

Question

I'm trying to learn RxSwift concept and got stuck somewhere unfortunately. There is two different screen connected to my TabBarController. On my SettingsViewController, I'm getting two string values and creating a model, On TransactionListViewController, I need to observe changes on and make a new request to fill list.
On parent tab bar controller, I have a Variable and when didLoadCall I'm subscribing this model with wallet.asObservable().subscribe
On SettingViewController when user presses the login button I'm trying to change UserModel with this code:
if let tabBar = parent?.parent as? TransactionTabBarController{
Observable.just(wallet).bind(to: tabBar.wallet)
}
I realized that onNext function for wallet.asObservable().subscribe is calling.
There is also another wallet model on my TransactionListViewController,
on viewDidLoad function I'm running this code:
wallet.asObservable().subscribe(onNext: { (wallet) in
APIClient.getTransaction(address: wallet.walletAddress)
.observeOn(MainScheduler.instance)
.subscribe(onNext: { (model) in
self.changeModels(items: model.result)
.bind(to: self.transactionTableView.rx.items(dataSource: self.dataSource))
.disposed(by: self.disposeBag)
})
.disposed(by: self.disposeBag)}, onError: nil, onCompleted: nil, onDisposed: nil)
.disposed(by: disposeBag)
I tried to set wallet on TabBar's onNext function and I got crush couple of times on TransactionListViewController.
Can anyone help me with that?

Answer 1

Sadly, your code sample is inscrutable. However, it seems as though you are asking how to transmit data between two view controllers that are connected through a tab bar view controller. Below is one way you could go about doing it...
In order to use this code, you only need to assign a function to TabBarController.logic which takes a TabBarController.Inputs as an input parameter and returns a TabBarController.Outputs. You could make this assignment in the AppDelegate.
The key thing to note in this code is that every ViewController subclass has a struct Inputs, a struct Outputs and a var logic in it.
The Inputs has all the UI elements that a user can input to (e.g., Buttons and TextFields,) and the Outputs has all the UI elements that the user can see (e.g., Label text, isHidden flags.)
The logic var is a closure that contains all the logic for that view controller. Note that it can be assigned to. That means that you can develop and test the logic independently of the view controller and you can provide a view controller with a different logic object if necessary depending on context.
For somewhat more complex example code that uses a Coordinator instead of embedding code in the container view controller, see this repo: https://github.com/danielt1263/RxEarthquake
class TabBarController: UITabBarController {
struct Inputs {
let login: Observable<Void>
}
struct Outputs {
let transactions: Observable<[Transaction]>
}
var logic: (Inputs) -> Outputs = { _ in fatalError("Forgot to set logic.") }
private let bag = DisposeBag()
override func viewDidLoad() {
super.viewDidLoad()
let settings = children[0] as! SettingsViewController
let transactionList = children[1] as! TransactionListViewController
let login = PublishSubject<Void>()
let outputs = logic(Inputs(login: login.asObservable()))
let bag = self.bag
settings.logic = { inputs in
inputs.login
.bind(to: login)
.disposed(by: bag)
return SettingsViewController.Outputs()
}
transactionList.logic = { inputs in
return TransactionListViewController.Outputs(transactions: outputs.transactions)
}
}
}
class SettingsViewController: UIViewController {
struct Inputs {
let login: Observable<Void>
}
struct Outputs {
}
var logic: (Inputs) -> Outputs = { _ in fatalError("Forgot to set logic.") }
private let bag = DisposeBag()
#IBOutlet weak var login: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
_ = logic(Inputs(login: login.rx.tap.asObservable()))
}
}
class TransactionListViewController: UIViewController {
struct Inputs {
}
struct Outputs {
let transactions: Observable<[Transaction]>
}
var logic: (Inputs) -> Outputs = { _ in fatalError("Forgot to set logic.") }
private let bag = DisposeBag()
#IBOutlet weak var transactionTableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
let output = logic(Inputs())
let dataSource = MyDataSource()
output.transactions
.bind(to: transactionTableView.rx.items(dataSource: dataSource))
.disposed(by: bag)
}
}