问将选中/未检查的任务保存到UserDefaults

EN

//
//  ListViewModel.swift
//

import Foundation

class ListViewModel: ObservableObject {
    
    @Published var items: [ItemModel] = [] {
        didSet {
            saveItems()
        }
    }
    
    let itemsKey: String = "task_items_list"
    
    init() {
        myTaskItems()
    }
    
    func myTaskItems() {
        let taskItems = [
            ItemModel(title: "This is the first task!", isCompleted: false),
            ItemModel(title: "This is the second task!", isCompleted: false),
            ItemModel(title: "This is the third task!", isCompleted: false),
            ItemModel(title: "This is the fourth task!", isCompleted: false),
            ItemModel(title: "This is the fifth task!", isCompleted: false)
        ]
        items.append(contentsOf: taskItems)
        
        guard
            let data = UserDefaults.standard.data(forKey: itemsKey),
            let savedTaskItems = try? JSONDecoder().decode([ItemModel].self, from: data)
        else { return }
        
        self.items = savedTaskItems
    }
    // Update TaskdItems Toggle
    func updateItem(item:ItemModel) {
        if let index = items.firstIndex(where: { $0.id == item.id }) {
            items[index] = item.updateCompletion()
        }
    }
    // Save to UserDefaults
    func saveItems() {
        if let encodedData = try? JSONEncoder().encode(items) {
            UserDefaults.standard.set(encodedData, forKey: itemsKey)
        }
    }
}

//  ItemModel.swift
//

import Foundation

struct ItemModel:Identifiable, Codable {
    let id: String
    let title: String
    let isCompleted: Bool
    
    init(id: String = UUID().uuidString, title: String, isCompleted: Bool) {
        self.id = UUID().uuidString
        self.title = title
        self.isCompleted = isCompleted
    }
    
    func updateCompletion() -> ItemModel {
        return ItemModel(id: id, title: title, isCompleted: !isCompleted)
    }
    
}

//
//  ListView.swift
//

import SwiftUI

struct ListView: View {
    
    @EnvironmentObject var listViewModel: ListViewModel
    
    var body: some View {
        List {
            ForEach(listViewModel.items) { item in
                ListRowView(item: item)
                    .onTapGesture {
                        listViewModel.updateItem(item: item)
                    }
            }
        }
        .listStyle(PlainListStyle())
        .navigationTitle("My Task List")
    }
    
    
    struct ListView_Previews: PreviewProvider {
        static var previews: some View {
            NavigationView {
                ListView()
            }
            .environmentObject(ListViewModel())
        }
    }
    
}

//
//  ListRowView.swift
//

import SwiftUI

struct ListRowView: View {
    
    let item: ItemModel
    
    var body: some View {
        HStack {
            Image(systemName: item.isCompleted ? "checkmark.circle" : "circle")
                .foregroundColor(item.isCompleted ? .green : .gray)
            Text(item.title)
            Spacer()
        }
        .font(.title2)
        .padding(.vertical, 8)
    }
}

struct ListRowView_Previews: PreviewProvider {
    
    static var item1 = ItemModel(title: "First item!", isCompleted: false)
    static var item2 = ItemModel(title: "Second item!", isCompleted: true)
    
    static var previews: some View {
        
        Group {
            ListRowView(item: item1)
            ListRowView(item: item2)
        }
        .previewLayout(.sizeThatFits)
    }
}

//
//  TaskListApp.swift
//

import SwiftUI

@main
struct TaskListApp: App {

    @StateObject var listViewModel: ListViewModel = ListViewModel()

    var body: some Scene {
        WindowGroup {
            NavigationView {
                ListView()
            }
            .environmentObject(listViewModel)
        }
    }
}