SwiftUI ObservedObject does not updated when new items are added from a different view

Question

I have a view model which handles the loading of new data once the app launches and when a new item is added. I have an issue when it comes to showing new items when are added from a new view, for example, a sheet or even a NavigationLink.

View Model

class GameViewModel: ObservableObject {
    //MARK: - Properties
    @Published var gameCellViewModels = [GameCellViewModel]()
    var game = [GameModel]()
    
    init() {
        loadData()
    }
    
    func loadData() {
        if let retrievedGames = try? Disk.retrieve("games.json", from: .documents, as: [GameModel].self) {
            game = retrievedGames
        }
        
        self.gameCellViewModels = game.map { game in
            GameCellViewModel(game: game)
        }
        print("Load--->",gameCellViewModels.count)
    }
    
    func addNew(game: GameModel){
        self.game.append(game)
        saveData()
        loadData()
    }
    
    private func saveData() {
        do {
            try Disk.save(self.game, to: .documents, as: "games.json")
        }
        catch let error as NSError {
            fatalError("""
                Domain: \(error.domain)
                Code: \(error.code)
                Description: \(error.localizedDescription)
                Failure Reason: \(error.localizedFailureReason ?? "")
                Suggestions: \(error.localizedRecoverySuggestion ?? "")
                """)
        }
    }
}

View to load the ViewModel data, leading add button is able to add and show data but the trailing which opens a new View does not update the view. I have to kill the app to get the new data.

    NavigationView{
        List {
            ForEach(gameList.gameCellViewModels) { gameList in
                CellView(gameCellViewModel: gameList)
            }
        }.navigationBarTitle("Games Played")
            .navigationBarItems(leading: Text("Add").onTapGesture {
                let arr:[Int] = [1,2,3]
                self.gameList.addNew(game: GameModel(game: arr))
                }, trailing: NavigationLink(destination: ContentView()){
                    Text("Play")
            })
    }

Play View sample

@State var test = ""
var body: some View {
    VStack(){
        TextField("Enter value", text: $test)
            .keyboardType(.numberPad)
        
        Button(action: {
            var arr:[Int] = []
            arr.append(Int(self.test)!)
            self.gameList.addNew(game: GameModel(game: arr))
        }) {
            Text("Send")
        }
    }
}

Can you show the ContentView() in trailing as it is the seemingly not working one. You just mention that it doesn't display the data but we have no insight of the View. ```trailing: NavigationLink(destination: ContentView())``` — Simon, Jul 11 '20 at 07:25

score 0 · Answer 1 · answered Jul 10 '20 at 20:35

To what I can see the issue seems to be here:

List {
   // Add id: \.self in order to distinguish between items 
   ForEach(gameList.gameCellViewModels, id: \.self) { gameList in                    
      CellView(gameCellViewModel: gameList)                    
   }
}

ForEach needs something to orientate itself on in order to know what elements are already displayed and which are not.

If this did not solve the trick. Please update the code you provided to Create a minimal, Reproducible Example

I already have identifiable in my model. I have found the issue to be something different. I have updated the question. — G B, Jul 10 '20 at 22:30

SwiftUI ObservedObject does not updated when new items are added from a different view

1 Answers1