SwiftUI列表需要精确的位置来呈现结果，因此如果没有[0]等，就不会呈现结果。

Question

当试图解析来自SwiftUI中REST端点的一些数据时，我很难正确地呈现到列表中。

在下面的示例中，我的列表需要精确的数组位置来呈现结果，所以如果没有[0]等，它就不会显示任何内容。

我习惯于在JavaScript中使用for循环来解决这种类型的问题，并对其进行迭代以将每个数组位置分配给[i]，但是在SwiftUI中，我很难做到同样的事情。

我认为如何处理嵌套的JSON对象可能是个问题，但现在开始。我也相信，这可能是一个简单的解决方案，我只是在这里模糊。

我已经创建了一个测试端点，如果您需要在本地运行它，可以从中获取它(这已经在下面的示例中了)。

来澄清我想在这里做什么。我想在数组上迭代以引用(例如) Text(item.objects.title)，而不必指定我要寻找的数组中的哪一项。遗憾的是，使用ForEach并不有效，因为List(viewModel.items, id: \.self) { item in }实际上是在复制ForEach循环，而且也不起作用。

模型

struct ObjectResponse: Hashable, Decodable {
    let objects: [Object]
}

struct Object: Hashable, Decodable {
    let slug: String
    let title: String
    let metadata: Metadata
}

struct Metadata: Hashable, Decodable {
    let published: String
    let url: String
    let snippet: String
    let read: Bool
}

ViewModel

class ContentViewModel: ObservableObject {
    @Published var items: [ObjectResponse] = []
    func fetchData() {
        let api = "https://api.cosmicjs.com/v2/buckets/a5e294b0-55ee-11ec-942e-ef0a04148eb7/objects?pretty=true&query=%7B%22type%22%3A%22bookmarks%22%7D&read_key=fufvo5ceSy1W88afkchDIRjYrUIzErPw9YzcW2vQV1SxKqjNHo&limit=20&props=slug,title,content,metadata,"
        
        guard let url = URL(string: api) else { return }
        
        URLSession.shared.dataTask(with: url) { (data, response, error) in
            do {
                if let data = data {
                    let result = try JSONDecoder().decode(ObjectResponse.self, from: data)
                    DispatchQueue.main.async {
                        self.items = [result]
                        
                        /* Prints out everything nicely
                        result.objects.forEach {
                             print($0.title)
                        }
                        */
                        
                    }
                } else {
                    print("No data")
                }
            } catch (let error) {
                print(error)
            }
        }.resume()
    }
}

内容视图

struct ContentView: View {
    @ObservedObject var viewModel = ContentViewModel()
    
    var body: some View {
        NavigationView {
            List(viewModel.items, id: \.self) { item in
                VStack(alignment: .leading) {
                    Text(item.objects[0].title) // Requires me to provide array position
                }
            }
            .navigationTitle("Bookmarks")
        }
        .onAppear(perform: {
            viewModel.fetchData()
        })
    }
}

示例JSON响应

{
  "objects": [
    {
      "slug": "the-navigation-bar-isnt-hidden-as-expected-in-swiftui",
      "title": "The Navigation Bar Isn’t Hidden as Expected in SwiftUI",
      "content": null,
      "metadata": {
        "published": "28 Nov 2021 at 16:30",
        "url": "https://betterprogramming.pub/swiftui-navigationbar-is-not-really-hidden-as-you-expect-785ff0425c86",
        "snippet": "",
        "read": true
      }
    },
    {
      "slug": "hey-facebook-i-made-a-metaverse-27-years-ago",
      "title": "Hey, Facebook, I Made a Metaverse 27 Years Ago",
      "content": null,
      "metadata": {
        "published": "28 Nov 2021 at 21:39",
        "url": "https://www.theatlantic.com/technology/archive/2021/10/facebook-metaverse-was-always-terrible/620546/",
        "snippet": "Michel Baret / Gamma-Rapho / Getty In a booth at Ted’s Fish Fry, in Troy, New York, my friend Daniel Beck and I sketched out our plans for the metaverse. ",
        "read": true
      }
    },
    {
      "slug": "when-big-tech-buys-small-tech-benedict-evans",
      "title": "When big tech buys small tech — Benedict Evans",
      "content": null,
      "metadata": {
        "published": "28 Nov 2021 at 21:39",
        "url": "https://www.ben-evans.com/benedictevans/2021/11/12/when-big-tech-buys-small-tech",
        "snippet": "Acquisitions are a big part of the discussion around competition in tech today, and a big set of questions. It’s easy to say that we wouldn’t let Amazon buy Zappos or Google buy DoubleClick again, but everyone’s favourite puzzle is Instagram. ",
        "read": false
      }
    }
  ],
  "total": 171,
  "limit": 3
}

Answer 1

好了，解决了，多亏了jnpdx的一点帮助。需要通过ForEach循环进一步钻入数组，如下所示：

List(viewModel.items, id: \.self) { item in
 ForEach(item.objects, id: \.self) { bookmark in
   VStack(alignment: .leading) {
    Text(bookmark.title)
   }
 }
}