【Swift】タスクキル（アプリの再起動）をしてもアプリ内のTextFieldの文字を保持しておきたい

前提

YouTubeの動画を参考にメモウィジェットアプリを作成しました。

機能としましては、アプリ内のTextFieldに文字を入力すると、入力した文字がウィジェットに表示されるアプリです。

実現したいこと

アプリをタスクキルすると、Widgetに表示されている文字は表示されたままなのですが、アプリ内のTextFieldの文字が消えてしまいます。
そのため、タスクキルをしてもTextFieldの文字を保持できるようにしたいです。

該当のソースコード

ViewController.swift
1import UIKit
2
3class ViewController: UIViewController {
4
5    @IBOutlet weak var txtText: UITextField!
6    override func viewDidLoad() {
7        super.viewDidLoad()
8        storeData(text: "メモを入力しよう")
9    }
10
11    @IBAction func btnStoreText(_ sender: Any) {
12        storeData(text: txtText.text ?? "--")
13    }
14    
15    func storeData(text : String) {
16        let storedata = StoreData(showText: text)
17        let primaryData = PrimaryData(storeData: storedata)
18        primaryData.encodeData()
19    }
20}

WidgetExtension.swift
1import WidgetKit
2import SwiftUI
3import Intents
4
5struct Provider: IntentTimelineProvider {
6    @AppStorage("CreateWidget", store: UserDefaults(suiteName: "group.isseiueda")) var primaryData : Data = Data()
7    func placeholder(in context: Context) -> SimpleEntry {
8        let storeData = StoreData(showText: "-")
9        return SimpleEntry(storeData : storeData, configuration: ConfigurationIntent())
10    }
11
12    func getSnapshot(for configuration: ConfigurationIntent, in context: Context, completion: @escaping (SimpleEntry) -> ()) {
13        guard let storeData = try? JSONDecoder().decode(StoreData.self, from: primaryData) else {
14            return
15        }
16        let entry = SimpleEntry(storeData: storeData, configuration: configuration)
17        completion(entry)
18    }
19
20    func getTimeline(for configuration: ConfigurationIntent, in context: Context, completion: @escaping (Timeline<Entry>) -> ()) {
21//        var entries: [SimpleEntry] = []
22//
23//        // Generate a timeline consisting of five entries an hour apart, starting from the current date.
24//        let currentDate = Date()
25//        for hourOffset in 0 ..< 5 {
26//            let entryDate = Calendar.current.date(byAdding: .hour, value: hourOffset, to: currentDate)!
27//            let entry = SimpleEntry(date: entryDate, configuration: configuration)
28//            entries.append(entry)
29//        }
30        guard let storeData = try? JSONDecoder().decode(StoreData.self, from: primaryData) else {
31            return
32        }
33        let entry = SimpleEntry(storeData: storeData, configuration: configuration)
34        
35        let timeline = Timeline(entries: [entry], policy: .never)
36        completion(timeline)
37    }
38}
39
40struct SimpleEntry: TimelineEntry {
41    let date: Date = Date()
42    let storeData : StoreData
43    let configuration: ConfigurationIntent
44}
45
46struct WidgetExtensionEntryView : View {
47    var entry: Provider.Entry
48
49    var body: some View {
50        Text(entry.storeData.showText)
51    }
52}
53
54struct WidgetExtension: Widget {
55    let kind: String = "WidgetExtension"
56
57    var body: some WidgetConfiguration {
58        IntentConfiguration(kind: kind, intent: ConfigurationIntent.self, provider: Provider()) { entry in
59            WidgetExtensionEntryView(entry: entry)
60        }
61        .configurationDisplayName("My Widget")
62        .description("This is an example widget.")
63    }
64}
65
66struct WidgetExtension_Previews: PreviewProvider {
67    static let storeData =  StoreData(showText: "-")
68    static var previews: some View {
69        WidgetExtensionEntryView(entry: SimpleEntry(storeData: storeData, configuration: ConfigurationIntent()))
70            .previewContext(WidgetPreviewContext(family: .systemMedium))
71    }
72}

StoreData.swift
1import Foundation
2
3struct StoreData : Codable {
4    var showText : String
5}

PrimaryData.swift
1import SwiftUI
2import WidgetKit
3
4struct PrimaryData {
5    @AppStorage("CreateWidget", store: UserDefaults(suiteName: "group.isseiueda")) var primaryData : Data = Data()
6    let storeData : StoreData
7    
8    func encodeData() {
9        guard let data = try? JSONEncoder().encode(storeData) else {
10            return
11        }
12        primaryData = data
13        WidgetCenter.shared.reloadAllTimelines()
14    }
15    
16}