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ObservedObject resets when I update the view using a property. Hence it leads to loss of data

I have an issue where the ViewModel would re-initialize when view is updated.

I have 2 views, SongListView and PlayerView which share an object of Player. When player's Playing state is changed (isPlaying == true), the viewModel in SongListView resets and becomes empty array. Due to which, the list on my view becomes empty.

enter image description here

SongListView:

struct SongListView: View {

    @ObservedObject var model: SongListViewModel = SongListViewModel() // This resets when player.isPlaying is set to true

    @ObservedObject var player: Player

    var body: some View {

        List(model.songs, id: \.id) { song in
            Button(action: {
                self.player.play(link: song.link)
            }) {
                TitleRowView(title: song)
            }
        }
        .onAppear {
            self.model.get()
        }
        .navigationBarTitle(Text("Songs"), displayMode: .inline)
    }
}

SongListViewModel:

class SongListViewModel: ObservableObject {

    @Published var songs: [Song] = [Song(id: 2, name: "ish", link: "ishm")] // When I tap the row, the songs var is re-initialized

    func get() {

        guard let url = URL(string: "apiPath") else { return }

        URLSession(configuration: URLSessionConfiguration.default).dataTask(with: url) {data, response, error 
               // Some more code
               self.songs = data
        }.resume()
    }
}

PlayerView:

struct PlayerView: View {

    @ObservedObject var player: Player

    var body: some View {
        HStack {
            Button(action: {
                if self.player.isPlaying {
                    self.player.pause()
                } else {
                    self.player.play()
                }
            }) {
                // This change causes the viewModel to reset to empty array
                if self.player.isPlaying { 
                    Image(systemName: "pause.fill")
                        .resizable()
                } else {
                    Image(systemName: "play.fill")
                        .resizable()
                }
            }
        }
    }
}

Player:

class Player : ObservableObject
{

    @Published var isPlaying: Bool = false

    private var player: AVPlayer?

    // This method is called when the user taps on a row in List
    func play(link: String) {
        guard let url = URL(string: link) else { return }
        let playerItem = AVPlayerItem(url: url)
        player = AVPlayer(playerItem: playerItem)
        player?.play()
        isPlaying = true // If I comment this line, the songs list in viewModel does not changes
    }    
}

Thanks in Advance!

UPDATE: Still doesn't work

struct SongListView: View {

    @ObservedObject var model: SongListViewModel

    var body: some View {
        // View 
    }
}

struct CategoryListView: View {
    var categoryData : [Category]
    @ObservedObject var player: Player

    var body: some View {
        List(categoryData, id: \.id) { category in
            if category.id == 3 {
                NavigationLink(destination: SongListView(model: SongListViewModel(), player: self.player)) {
                    TitleRowView(title: category)
                }
            }

        }
    }
}
like image 837
Ishmeet Avatar asked Oct 21 '25 04:10

Ishmeet


1 Answers

Using @StateObject instead of @ObservedObject worked for me.

A property marked as @StateObject will keep its initially assigned ObservedObject instance as long as the view is needed, even when the struct gets recreated by SwiftUI.

This allows you to maintain the state of your ObservedObject data.

like image 196
Leonardo Lovera Avatar answered Oct 22 '25 18:10

Leonardo Lovera



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