ViewModifier for DynamicViewContent?

Question

I would like to do something like this:

struct HandleUrlDropModifier<Content>: ViewModifier where Content: DynamicViewContent {
    @Environment(\.modelContext) var modelContext

    var content: Content

    func body(content: Content) -> some View {
        content
            .dropDestination(for: URL.self) { items, index in
                // index is Int
                handleUrlDrop(items, at: index)
            }
    }

    func handleUrlDrop(_ items: [URL], at index: Int) {
        modelContext.insert(...)
    }
}

Is that possible somehow?

---

What I've tried

Writing it as a direct extension doesn't work, since I want to use an @Environtment variable:

extension DynamicViewContent {
    @Environment(\.modelContext) var modelContext // <- not possible
    
    func handleUrlDrop() -> some View {
        self
        .dropDestination(for: URL.self) { items, index in
            modelContext.insert(...)
        }
   }
}

This works for regular Views, but the .dropDestination action is different for a DynamicViewContent:

struct HandleUrlDropModifier: ViewModifier {
    @Environment(\.modelContext) var modelContext

    func body(content: Content) -> some View {
        content
            .dropDestination(for: URL.self) { items, location in
                // location is CGPoint
                handleUrlDrop(items)
                return true
            }
    }

    func handleUrlDrop(_ items: [URL]) {
        modelContext.insert(...)
    }
}

Answer 1

Instead of a view modifier, write a View that wraps a DynamicViewContent and adds the dropDestination modifier. Then you can wrap this view with a DynamicViewContent extension, so that it looks like a view modifier.

// this view can conform to DynamicViewContent too!
struct HandleURLDropView<Content: DynamicViewContent>: DynamicViewContent {
    
    @Environment(\.modelContext) var modelContext

    let content: Content
    
    init(@ViewBuilder content: () -> Content) {
        self.content = content()
    }
    
    var body: some View {
        content.dropDestination(for: URL.self) { items, index in
            handleUrlDrop(items)
        }
    }

    func handleUrlDrop(_ items: [URL]) {
        // ...
    }
    
    // DynamicViewContent conformance
    var data: Content.Data { content.data }
}

extension DynamicViewContent {
    func handleURLDrop() -> some DynamicViewContent {
        HandleURLDropView {
            self
        }
    }
}