Question

在我的多维列表中，尝试删除行时遇到问题-线程1：致命错误：索引超出范围：

struct Parent: Identifiable {
    let id = UUID()
    let name: String
    var children: [Child]?
}

struct Child: Identifiable {
    let id = UUID()
    let name: String
}

class AppState: ObservableObject {
    @Published var parents: [Parent]
    init() {
        self.parents = [
            Parent(name: "Foo", children: [Child(name: "bar")]),
            Parent(name: "FooBar", children: nil)
        ]
    }
}

struct ContentView: View {
    @EnvironmentObject var appState: AppState
    var body: some View {
        NavigationView {
            List {
                ForEach (0..<appState.parents.count) { parentIndex in
                    NavigationLink (destination: ChildrenView(parentIndex: parentIndex).environmentObject(self.appState)) {
                        Text(self.appState.parents[parentIndex].name) // Thread 1: Fatal error: Index out of range
                    }
                }
                .onDelete(perform: deleteItem)
            }
        }
    }
    private func deleteItem(at indexSet: IndexSet) {
        self.appState.parents.remove(atOffsets: indexSet)
    }
}

struct ChildrenView: View {
    @EnvironmentObject var appState: AppState
    var parentIndex: Int
    var body: some View {
        List {
            ForEach (0..<(appState.parents[parentIndex].children?.count ?? 0)) { childIndex in
                Text(self.appState.parents[self.parentIndex].children![childIndex].name)
            }
        }
    }
}

我在一个具有更多代码的更大项目中遇到这个问题时，重新构建了这种情况。尤其是当我尝试删除有孩子的父母时，在“孩子视图”中出现了问题。对于没有孩子的父母，我可以将其删除。在这段代码中，我根本无法删除行。

我认为问题与parentIndex有关，在通过可观察对象更改重新加载视图时，import random def lottery(ticket): """ Compare lottery ticket against lottery draws and print how many draws have taken place to match the ticket. """ count = 0 run = True while run: lotto_num = [random.randint(1, 49) for _ in range(6)] lotto_num[-1] = random.randint(1, 7) if lotto_num != ticket: print(f"No match! Your ticket {ticket}, Lottery ticket {lotto_num}") count += 1 else: print(f"Match! Your ticket {ticket} lottery ticket {lotto_num}") print(f"{count} draws") run = False lottery([11, 12, 36, 39, 46, 1])并没有减少。

Answer 1

发生此问题是因为foreach循环中的范围是恒定的。必须将其更改为：

ForEach (appState.parents.indices, id: \.self) { parentIndex in

如何解决致命错误：索引超出范围

1 个答案: