MVVM and RxSwift for Search Screen - ios

Question

In purpose of education MVVM and RxSwift I want to build simple search screen, which will have a table view and a search bar. When user types something into the search bar I will show what he have in this table. Sounds pretty simple, but I can't find any tutorial which suits me.
I have already written all code in view controller, I just can't understand have to observe search text changes and then call database method, which will filter items by search text.
Some code, which I already have.
My ViewController
import Foundation
import UIKit
import RxSwift
import RxCocoa
class PlaceSearchViewController: UIViewController {
//MARK: -
#IBOutlet weak var searchBar: UISearchBar!
#IBOutlet weak var tableView: UITableView!
//MARK: - Dependencies
private var viewModel: PlaceSearchViewModel!
private let disposeBag = DisposeBag()
//MARK: - Lifecycle
override func viewDidLoad() {
super.viewDidLoad()
viewModel = PlaceSearchViewModel()
addBindsToViewModel(viewModel)
}
//MARK: - Rx
private func addBindsToViewModel(viewModel: PlaceSearchViewModel) {
searchBar.rx_text.bindTo(viewModel.searchTextObservable)
viewModel.placesObservable.bindTo(tableView.rx_itemsWithCellFactory) {
(tableView: UITableView, index, place: Place) in
let indexPath = NSIndexPath(forItem: index, inSection: 0)
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as PlaceCell
cell.configureWithObject(place)
return cell
}
.addDisposableTo(disposeBag)
tableView.rx_contentOffset
.subscribe { _ in
if self.searchBar.isFirstResponder() {
_ = self.searchBar.resignFirstResponder()
}
}
.addDisposableTo(disposeBag)
}
}
And my view model:
import Foundation
import RxSwift
import RxCocoa
class PlaceSearchViewModel {
//MARK: - Dependecies
private let disposeBag = DisposeBag()
//MARK: - Model
private let placesObservable: Observable<[Place]>
var searchTextObservable = Variable<String>("")
//MARK: - Set up
init() {
placesObservable = searchTextObservable.asObservable()
//wait 0.3 s after the last value to fire a new value
.debounce(0.3, scheduler: MainScheduler.instance)
//only fire if the value is different than the last one
.distinctUntilChanged()
//convert Observable<String> to Observable<[Place]>
.flatMapLatest { searchString -> Observable<[Place]> in
// some code here which I can't write.
}
//make sure all subscribers use the same exact subscription
.shareReplay(1)
}
}
Also, I have method [DataBase searchPlaces:searchText] which returns array of places - [Place]. I can't understand where and how place it in flatMapLatest of my ViewModel.

Answer 1

I create reactive wrapper for my DataBase by creating Observable<[Place]>.
This is my code
placesObservable = searchTextObservable.asObservable()
//wait 0.3 s after the last value to fire a new value
.debounce(0.0, scheduler: MainScheduler.instance)
//only fire if the value is different than the last one
.distinctUntilChanged()
//convert Observable<String> to Observable<Weather>
.flatMapLatest { searchString -> Observable<[AnyObject]> in
return TPReactiveDatabase.sharedInstance.searchPlacesByTitle(searchString)
}
//make sure all subscribers use the same exact subscription
.shareReplay(1)
And wrapper method searchPlacesByTitle
class TPReactiveDatabase: NSObject {
static let sharedInstance = TPReactiveDatabase()
// MARK: - Reactive Place database
func searchPlacesByTitle(title: String) -> Observable<[AnyObject]> {
return Observable.create { observer in
var places = [AnyObject]()
if (title.characters.count > 0) {
places = DBAccessKit.searchPlacesByTitle(title)
}
observer.on(.Next(places))
observer.on(.Completed)
return AnonymousDisposable {
}
}
}
}