xcode - 带有枚举源的 SwiftUI 选择器未启用

Question

我正在尝试了解新的 SwiftUI 选择器样式，尤其是来自非数组源的数据。我已经构建了一个带有枚举的选择器。我首先制作了一个只有选择器和关联枚举的简单应用程序。这按预期工作。

奇怪的是，当我将该代码复制并粘贴到另一个带有表单中其他控件的应用程序中时，选择器似乎处于非事件状态。我看到了，但不能点击它。

这是第一个应用程序(选择器工作):

struct ContentView: View {

    @State private var selectedVegetable = VegetableList.asparagus

    var body: some View {
        NavigationView {
            Form {
                Section {
                    Picker(selection: $selectedVegetable, label: Text("My Vegetables")) {
                        ForEach(VegetableList.allCases) { v in
                            Text(v.name).tag(v)
                            //use of tag makes no difference
                        }
                    }
                }
            }
            .navigationBarTitle("Picker with Enum")
        }
    }
}

enum VegetableList: CaseIterable, Hashable, Identifiable {
    case asparagus
    case celery
    case shallots
    case cucumbers

    var name: String {
        return "\(self)".map {
            $0.isUppercase ? " \($0)" : "\($0)" }.joined().capitalized
    }
    var id: VegetableList {self}
}

这是带有其他控件的应用程序(选择器不起作用)。

struct Order {
    var includeMustard = false
    var includeMayo = false
    var quantity: Int = 1
    var avocadoStyle = PepperoniStyle.sliced
    var vegetableType = VegetableType.none
    var breadType = BreadType.wheat
}

struct OrderForm: View {

    @State private var order = Order()
    @State private var comment = "No Comment"
    @State private var selectedVegetable = VegetableType.asparagus
    @State private var selectedBread = BreadType.rye

    func submitOrder() {}

    var body: some View {
        Form {
            Text("Vegetable Ideas")
                .font(.title)
                .foregroundColor(.green)
            Section {
                Picker(selection: $selectedVegetable, label: Text("Vegetables")) {
                    ForEach(VegetableType.allCases) { v in
                        Text(v.name).tag(v)
                    }
                }
                Picker(selection: $selectedBread, label: Text("Bread")) {
                    ForEach(BreadType.allCases) { b in
                        Text(b.name).tag(b)
                    }
                }
            }

            Toggle(isOn: $order.includeMustard) {
                Text("Include Mustard")
            }

            Toggle(isOn: $order.includeMayo) {
                Text("Include Mayonaisse")
            }

            Stepper(value: $order.quantity, in: 1...10) {
                Text("Quantity: \(order.quantity)")
            }

            TextField("Say What?", text: $comment)

            Button(action: submitOrder) {
                Text("Order")
            }
        }
        .navigationBarTitle("Picker in Form")
        .padding()

    }
}

enum PepperoniStyle {
    case sliced
    case crushed
}

enum BreadType: CaseIterable, Hashable, Identifiable {
    case wheat, white, rye, sourdough, seedfeast
    var name: String { return "\(self)".capitalized }
    var id: BreadType {self}
}

enum VegetableType: CaseIterable, Hashable, Identifiable {
    case none
    case asparagus
    case celery
    case shallots
    case cucumbers
    var name: String {
        return "\(self)".map {
            $0.isUppercase ? " \($0)" : "\($0)" }.joined().capitalized   
    }
    var id: VegetableType {self}
}

Xcode 11 Beta 7、Catalina Beta 7
Preview 和 Simulator 之间没有行为差异。我一定是遗漏了
这里很简单。任何指导将不胜感激。

Answer 1

我将表单包装在 NavigationView 中，选择器现在按预期运行。一旦文档更完整，我需要研究一下，但也许这可以帮助其他人。