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.
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)
}
}
}
}
}
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.
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