Why does binding to the Picker not work anymore in swiftui?

Question

When I run a Picker Code in the Simulator or the Canvas, the Picker goes always back to the first option with an animation or just freezes. This happens since last Thursday/Friday. So I checked some old simple code, where it worked before that and it doesn't work for me there, too. This is the simple old Code. It doesn't work anymore in beta 3, 4 and 5.

struct PickerView : View {
    @State var selectedOptionIndex = 0

    var body: some View {
        VStack {
            Text("Option: \(selectedOptionIndex)")
            Picker(selection: $selectedOptionIndex, label: Text("")) {
                Text("Option 1")
                Text("Option 2")
                Text("Option 3")
            }
        }
    }
}

In my newer code, I used @ObservedObject, but also here it doesn't work. Also I don't get any errors and it builds and runs. Thank you for any pointers.

----EDIT----- Please look at the answer first

After the help, that I could use the .tag() behind all Text()like Text("Option 1").tag(), it now takes the initial value and updates it inside the view. If I use @ObservedObject like here:

struct PickerView: View {
    @ObservedObject var data: Model

    let width: CGFloat
    let height: CGFloat

    var body: some View {
        VStack(alignment: .leading) {
            Picker(selection: $data.exercise, label: Text("select exercise")) {
                    ForEach(data.exercises, id: \.self) { exercise in
                        Text("\(exercise)").tag(self.data.exercises.firstIndex(of: exercise))
                    }
                }
.frame(width: width, height: (height/2), alignment: .center)
            }
       }
    }
}  

Unfortunately it doesn't reflect changes on the value, if I make these changes in another view, one navigationlink further. And also it doesn't seem to work with the my code above, where I use firstIndex(of: exercise)

---EDIT--- Now the code above works if I change Text("\(exercise)").tag(self.data.exercises.firstIndex(of: exercise)) into Text("\(exercise)").tag(self.data.exercises.firstIndex(of: exercise)!) because it couldn't work with an optional.

Answer 1

I found a way to simplify the code a bit without the need of operating on indicies and tags.

At first, make sure to conform your model to Identifiable protocol like this (this is actually a key part, as it enables SwiftUI to differentiate elements):

public enum EditScheduleMode: String, CaseIterable, Identifiable {
    case closeSchedule
    case openSchedule
    
    public var id: EditScheduleMode { self }
    
    var localizedTitle: String { ... }
}

Then you can declare viewModel like this:

public class EditScheduleViewModel: ObservableObject {
    @Published public var editScheduleMode = EditScheduleMode.closeSchedule
    public let modes = EditScheduleMode.allCases
}

and UI:

struct ModeSelectionView: View {
    private let elements: [EditScheduleMode]
    @Binding private var selectedElement: EditScheduleMode
    
    internal init?(elements: [EditScheduleMode],
                   selectedElement: Binding<EditScheduleMode>) {
        self.elements = elements
        _selectedElement = selectedElement
    }
    
    internal var body: some View {
        VStack {
            Picker("", selection: $selectedElement) {
                ForEach(elements) { element in
                    Text(element.localizedTitle)
                }
            }
            .pickerStyle(.segmented)
        }
    }
}

With all of those you can create a view like this:

ModeSelectionView(elements: viewModel.modes, selectedElement: $viewModel.editScheduleMode)

Answer 2

The answer summarized:

1. With the .tag() behind the Options it works. It would look like following:

Picker(selection: $selectedOptionIndex, label: Text("")) {
                ForEach(1...3) { index in
                    Text("Option \(index)").tag(index)
                }
            }

2. If you use a range of Objects it could look like this:

Picker(selection: $data.exercises, label: Text("")) {
                ForEach(0..<data.exercises.count) { index in
                    Text("\(data.exercises[index])").tag(index)
                }
            }

I am not sure if it is intended, that .tag() is needed to be used here, but it's at least a workaround.