无法通过 ForEach 按钮更新 @State 变量（Int Counter）？

Question

尝试通过遍历 ForEach 按钮来更新计数器，但在 Xcode11 中收到以下错误：

Cannot convert value of type >'ForEach, >_ModifiedContent)>>, >PaddingLayout>>' to closure result type ''

已尝试添加@State 但仍无法更新 var characterList 中的计数

import SwiftUI

struct CharacterSelection:Identifiable {
    var id: Int
    var name : String
    var count: Int
}

import SwiftUI

struct ContentView : View {

    @State var charactersList = [
        CharacterSelection(id: 0, name: "Witch", count: 0),
        CharacterSelection(id: 1, name: "Seer", count: 1),
        CharacterSelection(id: 2, name: "Hunter", count: 0),
        CharacterSelection(id: 3, name: "Knight", count: 0)
    ]


    var body: some View {

        VStack(alignment:.leading) {
            ForEach(charactersList.identified(by: \.id)) {character in
                HStack{
                    Text(character.name)
                    Spacer()
                    Text("\(character.count) 

                    Button(action: { character.count += 1 }) {
                        Text("Button")
                    }

                }.padding(10)
            }
        }
    }
}

点击按钮时，var CharacterList 中相应索引的计数应该 += 1。

Answer 1

请注意，Arrays 和 CharacterSelection 都是 Value 类型，而不是 Reference 类型。如果您不知道其中的区别，请查看此页面：https://developer.apple.com/swift/blog/?id=10

为了使您的代码正常工作，您可以这样重写它：

struct ContentView : View {

    @State var charactersList = [
        CharacterSelection(id: 0, name: "Witch", count: 0),
        CharacterSelection(id: 1, name: "Seer", count: 1),
        CharacterSelection(id: 2, name: "Hunter", count: 0),
        CharacterSelection(id: 3, name: "Knight", count: 0)
    ]


    var body: some View {

        VStack(alignment:.leading) {
            ForEach(0..<charactersList.count) { i in
                HStack{
                    Text(self.charactersList[i].name)
                    Spacer()
                    Text("\(self.charactersList[i].count)")

                    Button(action: { self.charactersList[i].count += 1 }) {
                        Text("Button")
                    }

                }.padding(10)
            }

            Button(action: {
                self.charactersList.append(CharacterSelection(id: self.charactersList.count, name: "something", count: 0))
            }, label: {
                Text("Add CharacterSelection")
            })

        }
    }
}

无法通过 ForEach 按钮更新 @State 变量（Int Counter）？

Update @State variable (Int Counter) through ForEach button not possible?

foreach

swiftui

ios13