ContentView.swift

//
//  ContentView.swift
//  SwiftUIDataManagingSample
//
//  Created by Matthew Burke on 11/16/21.
//

import SwiftUI

struct ContentView: View {
    @Binding var items: [Item]

    var body: some View {
        List {
            ForEach(items) { item in
                HStack {
                    Text(item.name)
                    Spacer()
                    Text("\(item.value)")
                }
                .onTapGesture {
                    var b = binding(for: item)
                    b.update()
                }
            }
        }
        .navigationTitle("Items")
    }

    func binding(for item: Item) -> Binding<Item> {
        guard let index = items.firstIndex(where: { $0.id == item.id } ) else {
            fatalError("Can't find item in array.")
        }

        return $items[index]
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        NavigationView {
            ContentView(items: .constant(Item.items))
        }
        .preferredColorScheme(.light)

        NavigationView {
            ContentView(items: .constant(Item.items))
        }
        .preferredColorScheme(.dark)
    }
}

SwiftUIDataManagingSampleApp.swift

//
//  SwiftUIDataManagingSampleApp.swift
//  SwiftUIDataManagingSample
//
//  Created by Matthew Burke on 11/16/21.
//

import SwiftUI

@main
struct SwiftUIDataManagingSampleApp: App {
    @State private var items = Item.items

    var body: some Scene {
        WindowGroup {
            NavigationView {
                ContentView(items: $items)
            }
        }
    }
}

public struct Item: Identifiable {
    public static var items = [
        Item(name: "item 1"),
        Item(name: "item 2"),
        Item(name: "item 3"),
        Item(name: "item 4"),
        Item(name: "item 5"),
        Item(name: "item 6"),
        Item(name: "item 7"),
    ]

    public var id: UUID = UUID()
    public var value: Int
    public let name: String

    public init(name: String, value: Int = Int.random(in: 1...100)) {
        self.name = name
        self.value = value
    }

    public mutating func update() {
        value = Int.random(in: 1...100)
    }
}