dictionary - 将 SwiftUI Picker 绑定(bind)到字典中保存的值

Question

以下代码编译并运行，但只有绑定(bind)到数组中的值的选择器才能工作。那些在字典里的人失败了。知道为什么会这样吗？

import SwiftUI

struct ContentView: View {

    private var options : [String] = ["Bonjour", "Hello", "Hola"]

    @State private var choicesHeldInArray = [0, 2]
    @State private var choicesHeldInDict: [String: Int] = ["C3": 2, "C4":1]

    var body: some View {

        VStack {

            Picker(selection: $choicesHeldInArray[0], label: Text("Choice 1")) {
                ForEach(0 ..< options.count) {
                    Text(self.options[$0])
                }
            }

            Picker(selection: $choicesHeldInArray[1], label: Text("Choice 2")) {
                ForEach(0 ..< options.count) {
                    Text(self.options[$0])
                }
            }

            Picker(selection: $choicesHeldInDict["C3"], label: Text("Choice 3")) {
                ForEach(0 ..< options.count) {
                    Text(self.options[$0])
                }
            }

            Picker(selection: $choicesHeldInDict["C4"], label: Text("Choice 4")) {
                ForEach(0 ..< options.count) {
                    Text(self.options[$0])
                }
            }
        }
    }
}

Answer 1

Could the answer be something because of this?

简而言之您不能使用 ForEach 因为:

• 它会观察集合并监控运动。使用无序字典是不可能的。