SwiftUI + SwiftData で ToDo リスト を作ってみる 👉 https://android.benigumo.com/20231128/swiftui-swiftdata-todo/

Todo.swift

import Foundation
import SwiftData

@Model
final class Todo {
  var text: String
  var date: Date

  init(text: String = "", date: Date = Date()) {
    self.text = text
    self.date = date
  }
}

extension Date {
  func string(format: String = "yyyy-MM-dd HH:mm:ss") -> String {
    let formatter = DateFormatter()
    formatter.dateFormat = format
    return formatter.string(from: self)
  }
}

TodoList.swift

import SwiftUI
import SwiftData

struct TodoList: View {
  @Environment(\.modelContext) private var context
  @Query(sort: \Todo.date) private var todos: [Todo]
  @State private var selectedID: PersistentIdentifier?
  @State private var bottomID: PersistentIdentifier?
  @State private var text = ""
  @FocusState var focused: Bool

  var body: some View {
    NavigationStack {
      VStack(spacing: 0) {
        ScrollView {
          ForEach(todos) { todo in
            LazyVStack(alignment: .leading) {
              Text(todo.text)
                .font(.headline)
              Text(todo.date.string())
                .font(.caption)
                .foregroundStyle(.secondary)
            }
            .padding()
            .foregroundStyle(selectedID == todo.id ? .white : .black)
            .background(selectedID == todo.id ? .blue : .white)
            .onTapGesture {
              withAnimation {
                if selectedID == todo.id {
                  clear()
                } else {
                  selectedID = todo.id
                  text = todo.text
                }
              }
            }
          }
          .padding()
          .scrollTargetLayout()
        }
        .scrollPosition(id: $bottomID)
        .onAppear {
          withAnimation {
//            for todo in todos {
//              delete(todo: todo)
//            }
//            for i in 1 ..< 10000 {
//              insert(text: "\(i) どうするのこれ")
//            }
            bottomID = todos.last?.id
          }
        }
        HStack {
          TextField("", text: $text)
            .font(.system(.title3))
            .textFieldStyle(.roundedBorder)
            .focused($focused)

          Button {
            withAnimation {
              if selectedID != nil {
                update(todo: selectedTodo, text: text)
              } else {
                insert(text: text)
              }
            }
          } label: {
            Image(systemName: selectedID != nil ? "arrow.clockwise" : "plus")
              .frame(height: 25)
          }
          .buttonStyle(.borderedProminent)

          if selectedID != nil {
            Button {
              withAnimation {
                delete(todo: selectedTodo)
              }
            } label: {
              Image(systemName: "xmark")
                .frame(height: 25)
            }
            .buttonStyle(.borderedProminent)
          }

        }
        .padding()
      }
      .navigationTitle("Todo List")
    }
  }

  private func insert(text: String) {
    context.insert(Todo(text: text))
    clear()
    self.bottomID = todos.last?.id
  }

  private func delete(todo: Todo) {
    context.delete(todo)
    clear()
  }

  private func update(todo: Todo, text: String) {
    delete(todo: todo)
    insert(text: text)
    clear()
  }

  private func clear() {
    self.focused = false
    self.text = ""
    self.selectedID = nil
  }

  private var selectedTodo: Todo {
    return todos.first(where: { todo in todo.id == selectedID })!
  }
}

#Preview {
  TodoList()
    .modelContainer(for: Todo.self)
    .frame(width: 300)
}

【Swift】モデルクラスの ID に UUID() を使ってたらヤバい - PersistentIdentifier
👉 https://android.benigumo.com/20231205/persistentidentifier/