Ios SwiftUI-更改“中的属性”；onAppear“；不'；出示时不要更改工作表

我有一个按钮，当它被按下时，我会出示一张纸。此工作表在

列表中显示
选项.类别

问题是，当我在
ContentView
的
onAppear
中设置
选项.categories
时，工作表不会反映更改。它仍然是一个空列表

struct ViewOptions {
    public var categories = [String]()
}
struct ContentView: View {
    @State var presentingModal = false
    @State var options = ViewOptions()

    var body: some View {
        VStack {
            Text("Tap to present:")
            Button("Present") { presentingModal = true } /// set presentingModal to true, to present the sheet
            .sheet(isPresented: $presentingModal) {
                ModalView(options: options)
            }
        }
        .onAppear {
            options.categories = ["one", "two", "three", "four"]
        }
    }
}

struct ModalView: View {
    var options: ViewOptions
    var body: some View {
        List { /// display options.categories in a List
            ForEach(options.categories, id: \.self) { word in
                Text(word)
            }
        }
    }
}

结果（未显示任何内容！）：

但是如果我注释掉
.sheet
并将
ModalView
嵌入
ContentView
中，它就可以工作了

VStack {
    Text("Tap to present:")
       Button("Present") { presentingModal = true }
//     .sheet(isPresented: $presentingModal) { /// get rid of the sheet
           ModalView(options: options)
//     }
}
.onAppear {
    options.categories = ["one", "two", "three", "four"]
}

如何继续使用工作表，但在更改值时更新列表？
无需在出现时使用。您只需初始化一个新的ViewOptions对象：

struct ContentView: View {
    @State var presentingModal = false
    @State var options: ViewOptions = .init(categories:  ["one", "two", "three", "four"])

    var body: some View {
        VStack {
            Text("Tap to present:")
            Button("Present") {
                presentingModal = true
            }
            .sheet(isPresented: $presentingModal) {
                ModalView(options: options)
            }
        }
    }
}

这可能与iOS 14的更改有关：