动态选项卡栏项目计数 SwiftUI 导致应用程序崩溃

Question

这里有以下情况。基本上我想根据情况拥有动态数量的选项卡栏项目。在下面提供的示例中，当点击按钮时，它将在数组中间（索引 1）再添加一个选项卡，即先前所在的位置

case .five

。我遇到的问题是，当新的

.three

选项卡显示并且我单击它时，应用程序崩溃并出现以下错误：

"Layout requested for visible navigation bar, <SwiftUI.UIKitNavigationBar: 0x100710c50; baseClass = UINavigationBar; frame = (0 24; 1024 102); opaque = NO; autoresize = W; gestureRecognizers = <NSArray: 0x600000c63390>; layer = <CALayer: 0x60000026e5a0>> delegate=0x110016200, when the top item belongs to a different navigation bar. topItem = <UINavigationItem: 0x100712790> title='Hello' style=navigator leftItemsSupplementBackButton largeTitleDisplayMode=always, navigation bar = <SwiftUI.UIKitNavigationBar: 0x10951dc00; baseClass = UINavigationBar; frame = (0 24; 1024 102); opaque = NO; autoresize = W; gestureRecognizers = <NSArray: 0x600000c8b960>; layer = <CALayer: 0x60000028ad60>> delegate=0x10f052800, possibly from a client attempt to nest wrapped navigation controllers."

有趣的是，它只发生在 iOS 17+ 上，而不是 16 上。我收到错误的小 POC：

class ContentViewModel: ObservableObject {
    @Published var tabs: [Tab] = [.one, .five]

    static var shared = ContentViewModel()
}

struct ContentView: View {
    @State var selection: Tab = .one
    @StateObject var vm = ContentViewModel.shared

    var body: some View {
        TabView(selection: $selection) {
            ForEach(vm.tabs, id: \.self) { tab in
                tab
                    .tag(tab)
                    .tabItem {
                        Text(tab.rawValue)
                    }
            }
        }
    }
}

enum Tab: String {
    case one = "One"
    case three = "Three"
    case five = "Five"
}

extension Tab: View {
    var body: some View {
        NavigationStack {
            switch self {
            case .one:
                Text("One")
            case .three:
                Text("Three")
            case .five:
                Button("Change") {
                    if ContentViewModel.shared.tabs.count == 3 {
                        ContentViewModel.shared.tabs.removeSubrange(1...1)
                    } else {
                        ContentViewModel.shared.tabs.insert(.three, at: 1)
                    }
                }
                .navigationTitle("Hello")
            }
        }
    }
}

Answer 1

这是几个操作系统之前的一个错误，您应该提交一份报告，以便它再次得到修复，但作为解决方法，您可以为 TabView 设置一个 id。

    TabView(selection: $selection) {
        ForEach(vm.tabs, id: \.rawValue) { tab in
            tab
                .tag(tab)
                .tabItem {
                    Text(tab.rawValue)
                }
        }
    }.id(vm.tabs.count) // <——Here

这会重绘整个TabView，因此效率非常低。