如何有条件地呈现 SwiftUI 上下文菜单？

Question

Consider the following view code:

Text("Something")
.contextMenu {
    // Some menu options
}

This works fine. What I would like to do: present the contextMenu through a view modifier indirection. Something like this:

Text("Something")
.modifier(myContextMenu) {
    // Some menu options
}

Why: I need to do some logic inside the modifier to conditionally present or not present the menu. I can't work out the correct view modifier signature for it.

There is another contextMenu modifier available which claims that I can conditionally present the context menu for it. Upon trying this out, this does not help me, because as soon as I add contextMenu modifier to a NavigationLink on iOS, the tap gesture on it stops working. There is discussion in a response below.

How do I present a context menu using a view modifier?

Answer 1

Something like this?

Text("Options")
        .contextMenu {
            if (1 == 0) { // some if statements here
                Button(action: {
                    //
                }) {
                    Text("Choose Country")
                    Image(systemName: "globe")
                }
            }
    }

Answer 2

Here is a demo for optional context menu usage (tested with Xcode 11.2 / iOS 13.2)

struct TestConditionalContextMenu: View {
    @State private var hasContextMenu = false
    var body: some View {
        VStack {
            Button(hasContextMenu ? "Disable Menu" : "Enable Menu")
                { self.hasContextMenu.toggle() }
            Divider()
            Text("Hello, World!")
                .background(Color.yellow)
                .contextMenu(self.hasContextMenu ?
                    ContextMenu {
                            Button("Do something1") {}
                            Button("Do something2") {}
                    } : nil)
        }
    }
}

backup

Answer 3

Here's what I came up with. Not entirely satisfied, it could be more compact, but it works as expected.

struct ListView: View {    
    var body: some View {
        NavigationView {
            List {
                NavigationLink(destination: ItemView(item: "Something")) {
                    Text("Something").modifier(withiOSContextMenu())
                }.modifier(withOSXContextMenu())
            }
        }
    }
}

struct withOSXContextMenu: ViewModifier {
    func body(content: Content) -> some View {
        #if os(OSX)
        return content.contextMenu(ContextMenu {
            ContextMenuContent()
        })
        #else
        return content
        #endif
    }
}

struct withiOSContextMenu: ViewModifier {
    func body(content: Content) -> some View {
        #if os(iOS)
        return content.contextMenu(ContextMenu {
            ContextMenuContent()
        })
        #else
        return content
        #endif
    }
}

func ContextMenuContent() -> some View {
    Group {
        Button("Click me") {
            print("Button clicked")
        }
        Button("Another button") {
            print("Another button clicked")
        }
    }
}