TimestampContentView.swift

import SwiftUI

@available(iOS 16.0, *)
struct ContentView: View {
  @StateObject var viewModel = ViewModel()
  
  var body: some View {
    NavigationStack {
      Form {
        Section("Seconds since 1970") {
          TextField("Timestamp", value: $viewModel.timestamp,
                    formatter: viewModel.timestampFormatter)
          .keyboardType(.numberPad)
          .onChange(of: viewModel.timestamp) { timestamp in
            viewModel.date = Date(timeIntervalSince1970: timestamp)
          }
        }
        Section("UTC Date") {
          DatePicker("Select", selection: $viewModel.date)
            .environment(\.timeZone, .gmt)
            .onChange(of: viewModel.date) { date in
              viewModel.timestamp = date.timeIntervalSince1970
            }
        }
        Section("Local time zone") {
          Text(TimeZone.current.identifier)
          Text(viewModel.timeZoneOffsetString)
        }
        Section("Local Date") {
          DatePicker("Select", selection: $viewModel.date)
        }
      }
      .navigationTitle("Timestamp Converter")
    }
  }
}