swiftuiswiftui-picker

SwiftUI picker driven by an enum: value not updated


According to Apple's documentation regarding Picker in SwiftUI using an Enum, if the enum conforms to the Identifiable protocol in addition to CaseIterable, a picker iterating over all cases should update the bound variable natively.

I tested it, and it does not work as expected.

enum Flavor: String, CaseIterable, Identifiable {
    case chocolate
    case vanilla
    case strawberry

    var id: String { self.rawValue }
}

struct EnumView: View {
    @State private var selectedFlavor = Flavor.chocolate
    var body: some View {
        VStack {
            Picker("Flavor", selection: $selectedFlavor) {
                ForEach(Flavor.allCases) { flavor in
                    Text(flavor.rawValue.capitalized)//.tag(flavor)
                }
            }
        
            Text("Selected flavor: \(selectedFlavor.rawValue)")
        }
    }
}

enter image description here

However, if I pass a tag for each view, it works.

enter image description here

What's happening here? Is the Apple documentation wrong? The selectedFlavor variable expects a value of type Flavor, but the id used in the picker is actually a String.

Thanks.


Solution

  • For a Picker to work properly, its elements need to be identified.

    Note that the selectedFlavor variable is of type Flavor. Which means the options in the Picker should be identified as Flavors (not Strings).

    However, in your code your id is of type String:

    var id: String { self.rawValue }
    

    You can either: