Question

这里是初学者。我正在尝试在小部件中显示来自 JSON API 的数据。在应用程序中加载数据时，代码工作得很好，但是，当我在小部件上使用它时，相同的代码不起作用。我试过 .onAppear 但还是不行。

我的问题几乎与：How do I refresh Widgets in SwiftUI with JSON

它的一个回答说'像这样的异步 API 调用在小部件的视图中不起作用。您应该在时间线提供程序中收集 API 数据。” 正如这个问题所见How to refresh Widget data?

有人可以帮我解释一下吗？我不确定我必须修复什么，因为给定的示例将数据传递到时间线提供程序，而我的则不必。

struct Covid19WidgetView: View {
    
    @State private var covidData2: CovidData2?
    @State private var switchView = false
    
    var body : some View {
        if #available(iOS 15.0, *) {
            Rectangle()
                .foregroundColor(Color(red: 88/255, green: 76/255, blue: 244/255))
                .overlay{
                    VStack{
                        Text("Total cases:")
                            .foregroundColor(Color.white)
                            .fontWeight(.semibold)
   
                        Text("+ \(covidData2?.Confirmed ?? 0)")
                            .foregroundColor(Color.white)
                            .font(.system(size: 20))
                            .fontWeight(.semibold)
                            .onAppear{
                                loadData2()
                            }
                    }
                }
        } else {
            // Fallback on earlier versions
        }
    }
    
    private func loadData2() {
        guard let url = URL(string: "https://covid19.th-stat.com/json/covid19v2/getTodayCases.json") else {
            return
        }
        URLSession.shared.dataTask(with: url) { data, response, error in
            guard let data = data else {return}
            if let decodedData = try? JSONDecoder().decode(CovidData2.self, from: data){
                DispatchQueue.main.async {
                    self.covidData2 = decodedData
                }
            }
        }.resume()
    }
}

struct CovidData2: Decodable {
    var Confirmed: Int
    var Recovered: Int
    var Hospitalized: Int
    var Deaths: Int
    var NewConfirmed: Int
    var NewRecovered: Int
    var NewDeaths: Int
    var UpdateDate: String
}

struct Provider: TimelineProvider {
    func placeholder(in context: Context) -> SimpleEntry {
        SimpleEntry(date: Date())
    }

    func getSnapshot(in context: Context, completion: @escaping (SimpleEntry) -> ()) {
        let entry = SimpleEntry(date: Date())
        completion(entry)
    }

    func getTimeline(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()
        for hourOffset in 0 ..< 5 {
            let entryDate = Calendar.current.date(byAdding: .hour, value: hourOffset, to: currentDate)!
            let entry = SimpleEntry(date: entryDate)
            entries.append(entry)
        }

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

struct SimpleEntry: TimelineEntry {
    let date: Date
}

struct Covid19_WidgetEntryView : View {
    var entry: Provider.Entry

    var body: some View {
        Covid19WidgetView()
    }
}

@main
struct Covid19_Widget: Widget {
    let kind: String = "Covid19_Widget"

    var body: some WidgetConfiguration {
        StaticConfiguration(
            kind: kind,
            provider: Provider()
        ) { entry in
            Covid19_WidgetEntryView(entry: entry)
        }
        .configurationDisplayName("Covid-19 cases Tracker ??")
        .description("Display Thailand's new/total number of cases, recovered, and deaths from Covid-19")
        .supportedFamilies([.systemSmall])
    }
}

struct Covid19_Widget_Previews: PreviewProvider {
    static var previews: some View {
        Covid19_WidgetEntryView(entry: SimpleEntry(date: Date()))
            .previewContext(WidgetPreviewContext(family: .systemSmall))
    }
}

如何使用时间线提供程序刷新 SwiftUI 小部件数据？

0 个答案: