如何根据 SwiftUI 中的@State 更改导航视图的导航视图样式？

Question

我目前在 SwiftUI 与 Navigation View 一起工作。

问题： 我想使用 @State & @Binding.

从 Descendent View 更改 Navigation View Style

@Binding var defaultNavigationStyle: Bool
    
var body: some View {
    NavigationView {
        sidebar
            
        Text("Choose an Option from the Sidebar.")
            
        Text("Select an Element.")
    }
    .navigationViewStyle(defaultNavigationStyle ? DefaultNavigationViewStyle() : StackNavigationViewStyle())
}

Obviously, this does not work since the Elements have different Types. Error Message: Result Values in '?:' expression have mismatching types 'DefaultNavigationViewStyle' and 'StackNavigationViewStyle'

问题：如何使用@State & @Binding、而不创建完全不同的 NavigationView 来更改 Navigation View Style并失去所有 State?

Answer 1

您可以使用条件修饰符：

extension View {
    typealias ContentTransform<Content: View> = (Self) -> Content

    @ViewBuilder
    func conditionalModifier<TrueContent: View, FalseContent: View>(
        _ condition: Bool,
        ifTrue: ContentTransform<TrueContent>,
        ifFalse: ContentTransform<FalseContent>
    ) -> some View {
        if condition {
            ifTrue(self)
        } else {
            ifFalse(self)
        }
    }
}

并将其应用于 NavigationView:

NavigationView {
    sidebar
    Text("Choose an Option from the Sidebar.")
    Text("Select an Element.")
}
.conditionalModifier(
    defaultNavigationStyle,
    ifTrue: { [=11=].navigationViewStyle(DefaultNavigationViewStyle()) },
    ifFalse: { [=11=].navigationViewStyle(StackNavigationViewStyle()) }
)

如何根据 SwiftUI 中的@State 更改导航视图的导航视图样式？

How to change the Navigation View Style of a Navigation View depending on a @State in SwiftUI?

navigation

state

swift

navigationview

swiftui