【Flutter】iOS14の新機能、WidgetKitを操作する

let userDefaults = UserDefaults(suiteName: "hogeGroup")
userDefaults?.set("hoge", forKey: "hogeKey")

let userDefaults = UserDefaults(suiteName: "hogeGroup")
let date = userDefaults?.get("hoge", forKey: "hogeKey")

// dateには"hoge"が入る

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  var _counter = 0;

  Future<void> _incrementCounter() async {
    // カウンターをインクリメントする
    setState(() {
      _counter++;
    });

    // 更新後のカウンターをshared_preferencesで保存
    final prefs = await SharedPreferences.getInstance();
    await prefs.setInt('counter', _counter);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('WidgetKitで遊ぶ'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('ここの数字がウィジェットに表示されます'),
            Text('$_counter', style: TextStyle(fontSize: 100),),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

class _MyHomePageState extends State<MyHomePage> {
  static const _methodChannel = MethodChannel('work.hondakenya.flutterWidgetkit/sample');
  var _counter = 0;

  Future<void> _incrementCounter() async {
    // カウンターをインクリメントする
    setState(() {
      _counter++;
    });

    // 更新後のカウンターをshared_preferencesで保存
    final prefs = await SharedPreferences.getInstance();
    await prefs.setInt('counter', _counter);

    // Swiftのメソッド実行を依頼(通知)する（counterの値を保存する）
    try {
      final result = await _methodChannel.invokeMethod('setCounterForWidgetKit');
      print(result);
    } on PlatformException catch (e) {
      print('${e.message}');
    }

@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    
    let controller : FlutterViewController = window?.rootViewController as! FlutterViewController
    let channel = FlutterMethodChannel(name: "work.hondakenya.flutterWidgetkit/sample",
                                       binaryMessenger: controller.binaryMessenger)
    channel.setMethodCallHandler({
        (call: FlutterMethodCall, result: @escaping FlutterResult) -> Void in
        // ★channelにメソッドがinvokeされてきたら、呼ばれるようになる
    })
    
    GeneratedPluginRegistrant.register(with: self)
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }

import UIKit
import Flutter
import WidgetKit

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    
    let controller : FlutterViewController = window?.rootViewController as! FlutterViewController
    let channel = FlutterMethodChannel(name: "work.hondakenya.flutterWidgetkit/sample",
                                       binaryMessenger: controller.binaryMessenger)
    channel.setMethodCallHandler({
        (call: FlutterMethodCall, result: @escaping FlutterResult) -> Void in
        
        // Invokeされたメソッドが「setCounterForWidgetKit」の場合
        if call.method == "setCounterForWidgetKit" {
            self.setUserDefaultsForAppGroup(result: result)
        }
        
        result(FlutterMethodNotImplemented)
        return
    })
    
    GeneratedPluginRegistrant.register(with: self)
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
    
    private func setUserDefaultsForAppGroup(result: FlutterResult) {

        // FlutterのSharedPreferencesから取得
        let defaults = UserDefaults.standard
        let counter = defaults.integer(forKey: "flutter.counter") // flutterで指定したキーの先頭に「flutter.」が付与されている
        
        // 2: 1の結果をAppGroupのDefaultsに保存
        guard let userDefaults = UserDefaults(suiteName: "group.counter.hondakenya.sample") else {
            return result(FlutterError(code: "UNAVAILABLE",
                                       message: "setUserDefaultsForAppGroup Failed",
                                       details: nil))
        }
        userDefaults.setValue(counter, forKey: "counter")
        
        // WidgetKitを更新させる
        if #available(iOS 14.0, *) {
            WidgetCenter.shared.reloadAllTimelines()
        }
        
        result(userDefaults.integer(forKey: "counter"))
    }
}

struct SimpleEntry: TimelineEntry {
    let date: Date
    let counter: Int // ★追加した
    let configuration: ConfigurationIntent
}

    // WidgetKitが初めてレンダリングする時/特定のデータ保護資格の条件に合致したときに表示される
    // (ユーザデータとは関係ない、デフォルト値を設定することが多い)
    // https://developer.apple.com/documentation/widgetkit/timelineprovider/placeholder(in:)-6ypjs
    func placeholder(in context: Context) -> SimpleEntry {
        SimpleEntry(date: Date(), counter: 0, configuration: ConfigurationIntent())
    }

    // ウィジェットギャラリーに表示される
    func getSnapshot(for configuration: ConfigurationIntent, in context: Context, completion: @escaping (SimpleEntry) -> ()) {
        // AppGroupのUserDefaultからカウンターの値を取得
        let userDefaults = UserDefaults(suiteName: "group.counter.hondakenya.sample")
        let counter = userDefaults?.value(forKey: "counter") as? Int
        
        let entry = SimpleEntry(date: Date(), counter: counter ?? 0, configuration: configuration)
        completion(entry)
    }

    // 実際のウィジェットに表示される
    func getTimeline(for configuration: ConfigurationIntent, in context: Context, completion: @escaping (Timeline<Entry>) -> ()) {
        var entries: [SimpleEntry] = []

        // Generate a timeline consisting of five entries an hour apart, starting from the current date.
        let currentDate = Date()
        
        // AppGroupのUserDefaultからカウンターの値を取得
        let userDefaults = UserDefaults(suiteName: "group.counter.hondakenya.sample")
        let counter = userDefaults?.integer(forKey: "counter") ?? 0
        
        for hourOffset in 0 ..< 5 {
            let entryDate = Calendar.current.date(byAdding: .hour, value: hourOffset, to: currentDate)!
            let entry = SimpleEntry(date: entryDate, counter: counter, configuration: configuration)
            entries.append(entry)
        }

        let timeline = Timeline(entries: entries, policy: .atEnd)
        completion(timeline)
    }

struct counterViewEntryView : View {
    var entry: Provider.Entry

    var body: some View {
        Text(String(entry.counter)) // ★ここを修正
    }
}