在 iOS 14 小部件上渲染图像

问题描述

我正在开发 iOS 14 小部件扩展.

I'm developing a iOS 14 Widget extension.

我有 3 张图片要循环显示并创建一个时间线来显示这些图片.

I have 3 images to show in loop and creating a Timeline to show those images.

func getTimeline(in context: Context, completion: @escaping (Timeline<Entry>) -> ()) {
    var entries: [ImageEntry] = []
    let currentDate = Date()
    
    for i in 1 ..< 4 {
        let imageNumber = String(i)
        let currentImage = "image_" + imageNumber
        let entry = ImageEntry(date: currentDate,image: currentImage)
        entries.append(entry)
    }

    let nextUpdateDate = Calendar.current.date(byAdding: .minute, value: 5, to: currentDate)!
    let timeline = Timeline(entries: entries, policy: .after(nextUpdateDate))

    completion(timeline)
}


struct WidgetModuleEntryView : View {
var entry: Provider.Entry

var body: some View {
    Image(entry.image)
        .resizable()
        .scaledToFill()
    }
}

始终呈现第一张图像，但不呈现后续图像.

First image always rendering but subsequent images are not.

可能是什么问题?

推荐答案

构建时间线需要为每个条目指定明确的条目日期.政策参数用于重新创建下一个时间线.

Constucting timeline you need to specify explicit entry date for each entry. The policy parameter is for recreating next timeline.

所以你的 getTimeline 应该看起来像

So your getTimeline should look like

func getTimeline(in context: Context, completion: @escaping (Timeline<Entry>) -> ()) {
    var entries: [ImageEntry] = []
    let currentDate = Date()

    for i in 1 ..< 4 {
        let imageNumber = String(i)
        let currentImage = "image_" + imageNumber
        let entryDate = Calendar.current.date(byAdding: .minute, value: (i-1)*5, to: currentDate)!
        let entry = ImageEntry(date: entryDate, image: currentImage)
        entries.append(entry)
    }

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

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