swift - 如何允许 ForEach 布局项在 SwiftUI 中显示数组中的重复项？

Question

我正在使用多项选择答案测验应用程序。

var itemsTemp = ["ant","bat", "bear", "bee", "bird", "butterfly", "camel", "cat", "cheetah","chick", "chicken"]

更新 这里是我的测验应用程序的示例。

  let answerIndex = Int.random(in: 0...3) // for correct answer
  itemsTemp!.shuffle() // to multiple choose option change. 

这是错误：

线程1：致命错误：每个布局项只能出现一次

波纹管代码崩溃

LazyVGrid(columns: [GridItem(),GridItem()],spacing: 16) {
       ForEach(itemsTemp) { item in
            VStack {
                    Text(item).id(UUID())
                      .matchedGeometryEffect(id:UUID(), in: namespace, isSource: !show)
                      .onTapGesture{
                               print(" tapped!")
                        }
                    }.matchedGeometryEffect(id: "container\(UUID())", in: namespace)
                 }
              }

这是一个测验应用程序，因此可以选择多个选项来选择正确答案。数组项将在每个循环中多次出现。

所以需要每个布局项多次出现。

Answer 1

对于唯一标识符。使用模型数组而不是字符串数组。

首先，创建一个模型。

struct Item: Identifiable {
    var id = UUID()
    var name: String
}

那么，你的数组是

var itemsTemp: [Item] = [
    .init(name: "ant"),
    .init(name: "bat"),
    .init(name: "ant"),
    .init(name: "bear"),
    .init(name: "bee"),
    .init(name: "ant"),
    .init(name: "butterfly"),
    .init(name: "bear")
]

现在，你的循环是

//Other Code
ForEach(itemsTemp, id:\.id) { item in
    //Other Code
}
//Other Code

---

---

第二种方法是使用.indices.

//Other Code
ForEach(itemsTemp.indices) { index in
    let item = temsTemp[index]
    //Other Code
}
//Other Code

Answer 2

尝试一个模型：

struct Item: Identifiable {
var id = UUID()
var name: String
}


class Model: ObservableObject {
    var items: [Item] = [
        .init(name: "ant"),
        .init(name: "bat"),
        .init(name: "ant"),
        .init(name: "bear"),
        .init(name: "bee"),
        .init(name: "ant"),
        .init(name: "butterfly"),
        .init(name: "bear")
    ]
    @Published var itemsSuffled: [Item] = []
    
    init() {
        shuffle()
    }
    
    func shuffle() {
        itemsSuffled = items.shuffled()
    }
}

struct ContentView: View {
    
    @Namespace private var namespace
    @ObservedObject private var model: Model = Model()
    
    var body: some View {
        
        VStack {
            LazyVGrid(columns: [GridItem(),GridItem()],spacing: 16) {
                ForEach(model.itemsSuffled) { item in
                        VStack {
                            Text(item.name).id(UUID())
                                  .matchedGeometryEffect(id:UUID(), in: namespace, isSource: true)
                                  .onTapGesture{
                                           print(" tapped!")
                                    }
                                }.matchedGeometryEffect(id: "container\(UUID())", in: namespace)
                             }
            }
            Button(action: {
                model.shuffle()
            }, label: {
                Text("new shuffle")
            })
        }
        
    }
}