@AppStorage 值更改时，SwiftUI 小部件不更新

Question

我正在尝试让 SwiftUI 小部件在 @AppStorage 的值更改时根据命令进行更新。当我加载模拟器时，小部件从@AppStorage 更新为正确的值，但无论我尝试什么都不会再次更新。要在小部件中显示新值，需要关闭并重新打开模拟器。

在应用中查看：

import SwiftUI
import WidgetKit

struct MessageView: View {

    @AppStorage("message", store: UserDefaults(suiteName: "group.com.suiteName")) 
    var widgetMessage: String = ""

    var body: some View {
        VStack {
            Button(action: {
                self.widgetMessage = "new message"
                WidgetCenter.shared.reloadAllTimelines()
            }, label: { Text("button") })
        }

    }
}

小部件文件：

import WidgetKit
import SwiftUI
import Intents

struct Provider: IntentTimelineProvider {
    @AppStorage("message", store: UserDefaults(suiteName: "group.com.suiteName")) 
    var widgetMessage: String = ""
    
    func placeholder(in context: Context) -> SimpleEntry {
        SimpleEntry(date: Date(), message: "Have a great day!", configuration: ConfigurationIntent())
    }

    func getSnapshot(for configuration: ConfigurationIntent, in context: Context, completion: @escaping (SimpleEntry) -> ()) {
        let entry = SimpleEntry(date: Date(), message: "Have a great day!", configuration: configuration)
        completion(entry)
    }

    func getTimeline(for configuration: ConfigurationIntent, in context: Context, completion: @escaping (Timeline<Entry>) -> ()) {
        let entry = SimpleEntry(date: Date(), message: widgetMessage, configuration: configuration)
        let timeline = Timeline(entries: [entry], policy: .never)
        completion(timeline)
    }
}

struct SimpleEntry: TimelineEntry {
    let date: Date
    let message: String
    let configuration: ConfigurationIntent
}

struct statusWidgetEntryView : View {
    var entry: Provider.Entry

    var body: some View {
        VStack{
            Text(entry.message)
        }
    }
}

@main
struct statusWidget: Widget {
    let kind: String = "StatusWidget"

    var body: some WidgetConfiguration {
        IntentConfiguration(
            kind: kind,
            intent: ConfigurationIntent.self,
            provider: Provider()
        ) { entry in
            statusWidgetEntryView(entry: entry)
        }
        .configurationDisplayName("Note Widget")
        .description("Display note from a friend or group")
    }
}

Answer 1

AppStorage 应该在视图中，其他所有内容都保留在条目中

struct statusWidgetEntryView : View {
    @AppStorage("message", store: UserDefaults(suiteName: "group.com.suiteName")) 
    var widgetMessage: String = ""

    var entry: Provider.Entry

    var body: some View {
        VStack{
            Text(widgetMessage)
        }
    }
}

Answer 2

AppStorage+Widget 方法存在两个基本问题：

1. 您不能在 SwiftUI 之外使用 @AppStorage View - 尤其不能在 IntentTimelineProvider 中使用。
2. 小部件视图是静态的 - 即使您在小部件视图中使用@AppStorage，该值也只会被读取一次（击败@AppStorage 的观点）。

相反，您需要手动从UserDefaults读取值：

struct Provider: IntentTimelineProvider {
    let userDefaults = UserDefaults(suiteName: "group.com.suiteName")!

    func placeholder(in context: Context) -> SimpleEntry {
        SimpleEntry(date: Date(), message: "Have a great day!", configuration: ConfigurationIntent())
    }

    func getSnapshot(for configuration: ConfigurationIntent, in context: Context, completion: @escaping (SimpleEntry) -> ()) {
        let entry = SimpleEntry(date: Date(), message: "Have a great day!", configuration: configuration)
        completion(entry)
    }

    func getTimeline(for configuration: ConfigurationIntent, in context: Context, completion: @escaping (Timeline<Entry>) -> ()) {

        // read on every timeline refresh
        let widgetMessage = userDefaults.string(forKey: "message") ?? ""

        let entry = SimpleEntry(date: Date(), message: widgetMessage, configuration: configuration)
        let timeline = Timeline(entries: [entry], policy: .never)
        completion(timeline)
    }
}

Answer 3

您需要确保在调用WidgetCenter.shared.reloadAllTimelines() 之前将新值写入磁盘，我认为@AppStorage 没有办法做到这一点。在您的应用中，尝试直接设置 UserDefaults，然后在重新加载小部件之前调用 synchronize()：

Button(action: {
   let userDefaults = UserDefaults(suiteName: "group.com.suiteName")!
   userDefaults.set("new message", forKey: "message")
   userDefaults.synchronize()
   WidgetCenter.shared.reloadAllTimelines()
}, label: { Text("button") })

我知道文档声称 synchronize() 不再需要，但它是唯一对我有用的东西。 ¯\_(ツ)_/¯

在您的小部件中使用 UserDefaults 而不是 @AppStorage 也可能会有所帮助。

Answer 4

确保将您的应用组添加到签名和功能中的两个目标