SwiftUI multiple selection list

MultiSelectItemList.swift

import SwiftUI

/// UI View which presents a list of items, any number of which may
/// be selected. Each item must conform to `Identifiable` and
/// to `Hashable`.
struct MultiSelectItemList<T: Identifiable & Hashable>: View {
    private let items: [T]
    private let modified: (Set<T>) -> Void
    private let itemString: (T) -> String

    @State private var selected: Set<T>

    /// Initialize a MultiSelectItemList
    ///
    /// - Parameters:
    ///   - items: the items to be displayed
    ///   - selected: the currently selected items
    ///   - modified: callback, called when the selection changes
    ///   - itemString: method to get a displayable string label for a given item
    init(items: [T], selected: Set<T>, modified: @escaping (Set<T>) -> Void, itemString: @escaping (T) -> String) {
        self.items = items
        self.modified = modified
        self.itemString = itemString
        _selected = State(wrappedValue: selected)
    }

    var body: some View {
        ScrollView {
            ForEach(items) { item in
                MultiSelectItemRow(
                    item: item,
                    selected: selected.contains(item),
                    action: {
                    if selected.contains(item) {
                        selected.remove(item)
                    } else {
                        selected.insert(item)
                    }
                    modified(selected)
                },
                    itemString: itemString
                )
            }
        }
    }
}

MultiSelectItemRow.swift

import SwiftUI

struct MultiSelectItemRow<T>: View {
    let item: T
    let selected: Bool
    let action: () -> Void
    let itemString: (T) -> String

    var body: some View {
        HStack {
            icon
            Text(itemString(item))
            Spacer()
        }
        .background(background)
        .onTapGesture {
            action()
        }
    }

    var background: Color {
        if selected {
            return .accentColor
        } else {
            return .clear
        }
    }

    var icon: some View {
        ZStack {
            if selected {
                Image(systemName: "checkmark.circle")
            }
            EmptyView()
        }
        .frame(width: 30, height: 20, alignment: .center)
    }
}