IOS Widget（5）：小组件刷新机制

func getTimeline(for configuration: TimeTypeConfigurationIntent, 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 {
        // 下面这个代码表示，在当前日期上加上 hourOffset 个小时得到一个新的日期
        // .hour可以换成 .second .minute .day 等
        let entryDate = Calendar.current.date(byAdding: .hour, value: hourOffset, to: currentDate)!
        let entry = SimpleEntry(date: entryDate, configuration: configuration)
        entries.append(entry)
    }
    
    // 调用回调方法把生成好的时间线数据传递给系统
    // policy 表示刷新策略
    // .atEnd 表示，所有的时间线条目完成之后重新刷新一次，表现就是这个getTimeline方法被回调一次
    // .after(date: Date) 表示，多久时间结束后再刷新一次
    // .never表示时间轴走完就不刷了
    let timeline = Timeline(entries: entries, policy: .atEnd)
    completion(timeline)
}

static func prepareEntriesEveryMinute(_ completion: @escaping (Timeline<WidgetEntry>) -> ()) {
    // 第一次刷新时间：延迟2秒刷
    let firstDate = Provider.getFirstEntryDate()
    // 第二次刷新时间：第一个整分钟时刷
    let firstMinuteDate = Provider.getFirstMinuteEntryDate()
    
    var entries: [WidgetEntry] = []
    entries.append(WidgetEntry(date: firstDate))
    entries.append(WidgetEntry(date: firstMinuteDate))
    
    // 后面以第一个整点分钟开始，每次加一分钟刷
    for minuteOffset in 1 ..< 60 {
        guard let entryDate = Calendar.current.date(byAdding: .minute, value: minuteOffset, to: firstMinuteDate) else {
            continue
        }
        entries.append(WidgetEntry(date: entryDate))
    }
    let timeline = Timeline(entries: entries, policy: .atEnd)
    completion(timeline)
}

static func getFirstEntryDate() -> Date {
    let offsetSecond: TimeInterval = TimeInterval(2)
    var currentDate = Date()
    currentDate += offsetSecond
    return currentDate
}

// 获取第一个分钟时间点所处的时间点
static func getFirstMinuteEntryDate() -> Date {
    var currentDate = Date()
    let passSecond = Calendar.current.component(.second, from: currentDate)
    let offsetSecond: TimeInterval = TimeInterval(60 - passSecond)
    currentDate += offsetSecond
    return currentDate
}

// 指定刷新哪个组件
WidgetCenter.shared.reloadTimelines(ofKind: "com.mygame.character-detail")
// 刷新全部组件
WidgetCenter.shared.reloadAllTimelines()