swiftui - Select an item of list in NavigationStack for view restoration - Stack Overflow

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In my app there's a list in a NavigationStack for selecting an object for the next view. This is working well. But after restarting the app the selected item should be preselected. I've tried the following code:

@AppStorage("selectedIndex") private var selectedIndex: Int?

var body: some View {
   NavigationStack {
      List(selection: $selectedIndex) {
         ForEach(0..<myObjectsArray.count, id: \.self) { index in
            NavigationLink(destination: MyObjectView(selectedObject: myObjectsArray[index]) {
               VStack(alignment: .leading) {
                  HStack{
                     Text(myObjectsArray[index].name)
                     Text("- \(myObjectsArray[index].numbers) Employees")
                   }
                   Text("last Update: \(myObjectsArray[index].updated.ISO8601Format())")
                      .font(.footnote)
               }
            }
         }      
      }
   }
}

After restart of my app, the item of selectedIndex is highlighted but the corresponding view isn't shown. Where's my error?

In my app there's a list in a NavigationStack for selecting an object for the next view. This is working well. But after restarting the app the selected item should be preselected. I've tried the following code:

@AppStorage("selectedIndex") private var selectedIndex: Int?

var body: some View {
   NavigationStack {
      List(selection: $selectedIndex) {
         ForEach(0..<myObjectsArray.count, id: \.self) { index in
            NavigationLink(destination: MyObjectView(selectedObject: myObjectsArray[index]) {
               VStack(alignment: .leading) {
                  HStack{
                     Text(myObjectsArray[index].name)
                     Text("- \(myObjectsArray[index].numbers) Employees")
                   }
                   Text("last Update: \(myObjectsArray[index].updated.ISO8601Format())")
                      .font(.footnote)
               }
            }
         }      
      }
   }
}

After restart of my app, the item of selectedIndex is highlighted but the corresponding view isn't shown. Where's my error?

• swiftui
• view
• restore

Share Improve this question Follow edited Apr 1 at 21:24 user2836375 asked Apr 1 at 20:33 user2836375user2836375 13922 silver badges1111 bronze badges 8

• That is the wrong navigation link – lorem ipsum Commented Apr 1 at 21:03
• Yes, you are right. I've edited it. Now it's the right one. But the problem is like described. – user2836375 Commented Apr 1 at 21:14
• Nope still not the right one, look at the code example where you got this from – lorem ipsum Commented Apr 1 at 21:36
• I'm sorry, but I don't see it at the moment. What should the link look like? – user2836375 Commented Apr 1 at 21:43
• developer.apple/documentation/swiftui/navigationlink/… – lorem ipsum Commented Apr 1 at 22:14

 |  Show 3 more comments

1 Answer 1

Sorted by: Reset to default 1

Try this approach using NavigationPath and NavigationLink(value: index) as shown in the example code. Note you should not use index etc.. in the ForEach loop, use the actual Item.

// for testing
struct TheItem: Identifiable, Hashable {
    let id = UUID()
    var name: String
    var numbers: Int
}

struct ContentView: View {
    var body: some View {
        SelectionMode()
    }
}

struct SelectionMode: View {
    @AppStorage("selectedIndex") private var selectedIndex: Int?
    
    // for testing
    @State private var myObjectsArray = [
        TheItem(name: "item-1", numbers: 11),
        TheItem(name: "item-2", numbers: 22)
    ]
    
    @State private var path = NavigationPath() // <--- here
    
    var body: some View {
        NavigationStack(path: $path) {
            List {
                ForEach(0..<myObjectsArray.count, id: \.self) { index in
                    NavigationLink(value: index) {  // <--- here
                        VStack(alignment: .leading) {
                            HStack{
                                Text(myObjectsArray[index].name)
                                Text("- \(myObjectsArray[index].numbers) Employees")
                            }
                            Text("last Update)")
                                .font(.footnote)
                        }
                    }
                }
            }
            .navigationDestination(for: Int.self) { index in  // <--- here
                MyObjectView(selectedObject: myObjectsArray[index])
                    .onAppear {
                        selectedIndex = index
                    }
            }
        }
        .onAppear {
            if let ndx = selectedIndex {
                path.append(ndx)  // <--- here
            }
        }
    }
}
  
struct MyObjectView: View {
    let selectedObject: TheItem
    
    var body: some View {
        Text("MyObjectView \(selectedObject.name)")
    }
}

EDIT-1

Another more robust approach without using index, is to store the id of the item instead of the index.

For example:

struct TheItem: Identifiable, Hashable {
    let id: Int  // <--- here
    var name: String
    var numbers: Int
}

struct ContentView: View {
    @AppStorage("selectedItem") private var selectedItem: Int?
    
    // for testing
    @State private var myObjectsArray = [
        TheItem(id: 0, name: "item-0", numbers: 0),
        TheItem(id: 1,name: "item-1", numbers: 1)
    ]
    
    @State private var path = NavigationPath() // <--- here
    
    var body: some View {
        NavigationStack(path: $path) {
            List {
                ForEach(myObjectsArray) { item in  // <--- here
                    NavigationLink(value: item) {  // <--- here
                        VStack(alignment: .leading) {
                            HStack {
                                Text(item.name)
                                Text("- \(item.numbers) Employees")
                            }
                            Text("last Update)").font(.footnote)
                        }
                    }
                }
            }
            .navigationDestination(for: TheItem.self) { item in  // <--- here
                MyObjectView(selectedObject: item)
                    .onAppear {
                        selectedItem = item.id
                    }
                    .onDisappear {
                        selectedItem = -1 // <--- if required
                    }
            }
        }
        .onAppear {
            if let item = myObjectsArray.first(where: {$0.id == selectedItem ?? -1}) {
                path.append(item)  // <--- here
            }
        }
    }
}
   
struct MyObjectView: View {
    let selectedObject: TheItem
    
    var body: some View {
        Text("MyObjectView: \(selectedObject.name)  \(selectedObject.numbers)")
    }
}

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