来自if条件{ watchOS ()}的watchOS运行时错误

Question

据我所读到的关于条件视图的文章，这段代码应该可以工作。但事实并非如此。

struct Consts {
    static let myCondition = false //no difference if true or false
}

struct ContentView: View {
    @State var toggle: Bool = false
    var body: some View {
        List() {
            Text("Short Text is in first line")
            Text("Second Line Text is a little longer but not much")
            if Consts.myCondition {
                Text("This is a conditional text. As in: when the user hasn't purchased the option he / she don't need a hint how to use this feature.")
//            } else {
//                Text("else doesn't help either.")
            }
            Toggle("I also have a toggle but it has nothing to do with this.", isOn: $toggle)
            Text("Here we have a longer Text. Dont know what to type any more.")
            Text("More text which is longer than a few lines.")
            Text("Not so long Text")
        }
        .navigationTitle("Hints & Settings")
    }
}

它编译时没有警告或错误。它装载和显示良好，在模拟器和设备上。但是每次我从末尾向上滚动列表时，这个if condition { Text() }一出现，应用程序就会崩溃。

Fatal error: file SwiftUI, line 0
2021-03-07 06:36:26.548126+0100 WTFif WatchKit Extension[23163:641812] Fatal error: file SwiftUI, line 0

这不仅限于watchOS。它在iOS中以同样的方式复制，只是文本必须更长，这样在滚动时if condition { Text() }就变得不可见了。

我使用数组、条件范围和两个ForEach()块来解决错误。

struct ContentView: View {
    let myHints = ["Short Text is in first line",
                   "Second Line Text is a little longer but not much",
                   "This is a conditional text. As in: when the user hasn't purchased the option he / she don't need to hint how to use this feature.",
                   "Here we have a longer Text. Dont know what to type any more.",
                   "More text which is longer than a few lines.",
                   "Not so long Text"]
    var myUpperRange: ClosedRange<Int> {
        if Consts.myCondition {
            return 0...1
        } else {
            return 0...2
        }
    }
    var myLowerRange: ClosedRange<Int> {
        return 3...5
    }
    @State var toggle: Bool = false
    var body: some View {
        List() {
            ForEach (myUpperRange, id: \.self) { i in
                Text(myHints[i])
            }
            Toggle("I also have a toggle but it has nothing to do with this.", isOn: $toggle)
            ForEach (myLowerRange, id: \.self) { i in
                Text(myHints[i])
            }
        }
        .navigationTitle("Hints & Settings")
    }
}

我的问题基本上是:我是没有得到它，还是在Xcode / SwiftUI中找到了一个bug？我上面的代码有用吗？我可以做什么不同的工作，使它与简单的文本清单？

背景:我也有一个TabView和一个不崩溃的if condition { MyTab() }。我有必要担心这可能会以同样的方式崩溃吗？在装船之前，我也应该这样做吗？

PS:我正在使用Xcode 12.4 (12D4e)

Answer 1

显然，这是由iOS 15 Beta 4修复的:在我的测试设备上，我使用用Xcode 13 Beta 3编译的测试应用程序，在Beta 4更新之前出现了错误。在iOS 15 Beta 4更新之后，错误就消失了。因此，我认为有理由说iOS 15 Beta 4的更新确实修复了错误。