Why does my array get cleared out when observedobject gets updated? - ios

Question

I'm new to SwiftUI and MVVM and have been working on a podcast app and can't figure out for the life of me how to resolve this issue.
I have a list of podcast episodes with a button assigned to each in a VStack, when pressed, updates the userStore and presents a minimized player. When this happens, my list disappears and I get the ActivityIndicator and the list never reappears. I'm guessing the array gets cleared out whenever the state is updated. I don't want this behavior. What am I doing wrong?
struct PodcastDetailView: View {
#EnvironmentObject var userStore: UserStore
#ObservedObject var minimizableViewHandler: MinimizableViewHandler
#ObservedObject var player: Player = Container.player
#ObservedObject var podcastViewModel: PodcastViewModel
init(podcast: Podcast, player: Player = Container.player, minimizableViewHandler: MinimizableViewHandler) {
self.podcastViewModel = PodcastViewModel(podcast: podcast)
self.player = player
self.minimizableViewHandler = minimizableViewHandler
}
var body: some View {
ZStack{
Color(hex: "1B1D26")
.edgesIgnoringSafeArea([.all])
VStack(alignment: .leading, spacing: 10) {
PodcastDetailHeader(podcast: podcastViewModel.podcast)
if podcastViewModel.episodes.isEmpty {
ActivityIndicator()
.frame(width: 120, height: 120)
.foregroundColor(Color(hex: "813F97"))
.opacity(0.8)
.animation(.easeOut)
} else {
ScrollView {
VStack(alignment: .center, spacing: 10)
{
ForEach(podcastViewModel.episodes, id: \.self) { episode in
Button(action: {
if (self.player.state == .empty) {
self.userStore.selectedEpisode = episode
var newEpisodeData = self.podcastViewModel.episodes
if let selectedEpisodeIndex = newEpisodeData.firstIndex(where: {$0.id == episode.id}) {
newEpisodeData.remove(at: selectedEpisodeIndex)
newEpisodeData.insert(episode, at: newEpisodeData.startIndex)
self.player.setup(for: newEpisodeData)
self.minimizableViewHandler.present()
} else {
// item could not be found
}
} else {
print("new episode is " + episode.title)
self.userStore.selectedEpisode = episode
var newEpisodeData = self.podcastViewModel.episodes
if let selectedEpisodeIndex = newEpisodeData.firstIndex(where: {$0.id == episode.id}) {
newEpisodeData.remove(at: selectedEpisodeIndex)
newEpisodeData.insert(episode, at: newEpisodeData.startIndex)
self.player.setup(for: newEpisodeData)
self.player.play()
}
}
}) {
PodcastRowView(episode: episode)
.fixedSize(horizontal: false, vertical: true)
.padding(.top, 8)
}.buttonStyle(PlainButtonStyle())
.padding(.leading, 20)
.padding(.trailing, 10)
}
}
}
}
Spacer()
}
}
.navigationBarBackButtonHidden(true)
.navigationBarTitle(Text(self.podcastViewModel.podcast.title), displayMode: .inline)
.onAppear {
print("appearing")
self.podcastViewModel.loadEpisodes()
}
}
import Combine
import SwiftUI
class PodcastViewModel: ObservableObject {
private let apiService: APIService
private var episodesCancelable: Cancellable?
#Published var podcast: Podcast
#Published var episodes: [Episode] = []
init(podcast: Podcast, apiService: APIService = APIService()) {
self.podcast = podcast
self.apiService = apiService
}
deinit {
episodesCancelable?.cancel()
}
func loadEpisodes() {
episodesCancelable = apiService.episodes(for: podcast)
.receive(on: RunLoop.main)
.replaceError(with: [])
.assign(to: \.episodes, on: self)
}
}

Answer 1

I took FarouK's advice and used #StateObject. I had to change a couple of things but got it working.
struct PodcastDetailView: View {
#EnvironmentObject var userStore: UserStore
#ObservedObject var minimizableViewHandler: MinimizableViewHandler
#ObservedObject var player: Player = Container.player
#StateObject var podcastViewModel: PodcastViewModel
var podcast: Podcast
var body: some View {
ZStack{
Color(hex: "1B1D26")
.edgesIgnoringSafeArea([.all])
VStack(alignment: .leading, spacing: 10) {
PodcastDetailHeader(podcast: podcastViewModel.podcast)
if podcastViewModel.episodes.isEmpty {
ActivityIndicator()
.frame(width: 120, height: 120)
.foregroundColor(Color(hex: "813F97"))
.opacity(0.8)
.animation(.easeOut)
} else {
ScrollView {
VStack(alignment: .center, spacing: 10)
{
ForEach(podcastViewModel.episodes, id: \.self) { episode in
Button(action: {
if (self.player.state == .empty) {
self.userStore.selectedEpisode = episode
var newEpisodeData = self.podcastViewModel.episodes
if let selectedEpisodeIndex = newEpisodeData.firstIndex(where: {$0.id == episode.id}) {
newEpisodeData.remove(at: selectedEpisodeIndex)
newEpisodeData.insert(episode, at: newEpisodeData.startIndex)
self.player.setup(for: newEpisodeData)
self.minimizableViewHandler.present()
} else {
// item could not be found
}
} else {
print("new episode is " + episode.title)
self.userStore.selectedEpisode = episode
var newEpisodeData = self.podcastViewModel.episodes
if let selectedEpisodeIndex = newEpisodeData.firstIndex(where: {$0.id == episode.id}) {
newEpisodeData.remove(at: selectedEpisodeIndex)
newEpisodeData.insert(episode, at: newEpisodeData.startIndex)
self.player.setup(for: newEpisodeData)
self.player.play()
}
}
}) {
PodcastRowView(episode: episode)
.fixedSize(horizontal: false, vertical: true)
.padding(.top, 8)
}.buttonStyle(PlainButtonStyle())
.padding(.leading, 20)
.padding(.trailing, 10)
}
}
}
}
Spacer()
}
}
.navigationBarBackButtonHidden(true)
.navigationBarTitle(Text(self.podcastViewModel.podcast.title), displayMode: .inline)
.onAppear {
self.podcastViewModel.podcast = self.podcast
self.podcastViewModel.loadEpisodes()
}
}
import Combine
import SwiftUI
class PodcastViewModel: ObservableObject {
private let apiService: APIService
private var episodesCancelable: Cancellable?
#Published var podcast: Podcast = Podcast(id: "", title: "", image: URL(string: ""), thumbnail: URL(string: ""), totalEpisodes: 0, explicitContent: true, description: "", language: "", country: "", rss: URL(string: ""), latestPubDateMs: Date(), earliestPubDateMs: Date(), publisher: "")
#Published var episodes: [Episode] = []
init(apiService: APIService = APIService()) {
self.apiService = apiService
}
deinit {
episodesCancelable?.cancel()
}
func loadEpisodes() {
episodesCancelable = apiService.episodes(for: podcast)
.receive(on: RunLoop.main)
.replaceError(with: [])
.assign(to: \.episodes, on: self)
}
}