An adaptive modifier that seamlessly toggles between a modal Sheet on compact layouts (iPhone) and a Navigation Push on regular layouts (iPad), maintaining a native Apple user experience.

SheetOrNavigateItemModifier.swift

import SwiftUI

struct SheetOrNavigateItemModifier<Item: Identifiable & Hashable, Destination: View>: ViewModifier {
    @Binding var item: Item?
    @ViewBuilder let destination: (Item) -> Destination

    @Environment(\.horizontalSizeClass) private var horizontalSizeClass
    private var isRegular: Bool { horizontalSizeClass == .regular }

    func body(content: Content) -> some View {
        content
            // Regular: push using item-driven navigation
            .navigationDestination(item: navigationItemBinding) { value in
                destination(value)
            }
            // Compact: present as sheet
            .sheet(item: sheetItemBinding) { value in
                NavigationStack {
                    destination(value)
                }
            }
            // Optional: prevent mode-switch weirdness when size class changes mid-presentation
            .onChange(of: horizontalSizeClass) { _, _ in
                // If you want to be strict, uncomment:
                // if item != nil { item = nil }
            }
    }

    private var sheetItemBinding: Binding<Item?> {
        Binding(
            get: { isRegular ? nil : item },
            set: { newValue in
                guard !isRegular else { return }
                item = newValue
            }
        )
    }

    private var navigationItemBinding: Binding<Item?> {
        Binding(
            get: { isRegular ? item : nil },
            set: { newValue in
                guard isRegular else { return }
                item = newValue
            }
        )
    }
}

extension View {
    func sheetOrNavigate<Item: Identifiable & Hashable, Destination: View>(
        item: Binding<Item?>,
        @ViewBuilder destination: @escaping (Item) -> Destination
    ) -> some View {
        modifier(SheetOrNavigateItemModifier(item: item, destination: destination))
    }
}