SwiftUI构造与解码JSON

Question

使用URLSession从我的自定义API中获取水晶数据。试着按标题列出。

我知道这里有些地方不对，但不确定是什么。查找了所有的JSON字典解码，但没有运气。

Response结构是多余的还是我可以简单地用JSONDecoder()解码[String:Crystal]？如有任何指导和建议，我们将不胜感激。我知道如何使用数组来完成这个任务，但是字典让我很不爽。

GET https://lit-castle-74820.herokuapp.com/api/crystals

{
  "amethyst": {
    "composition": "silicon dioxide",
    "formation": "forms when gas bubbles occur in lava and become trapped",
    "colour": "purple",
    "metaphysical": [
      "calming",
      "healing",
      "especially for headaches",
      "fatigue, & anxiety"
    ]
  },
  "clear quartz": {
    "composition": "silicon dioxide",
    "formation": "forms when gas bubbles occur in lava and become trapped",
    "colour": "colourless or appears white",
    "metaphysical": "master healer for all ailments; amplifies the healing vibration of other stones placed nearby"
  },
  "moss agate": {
    "composition": "silicon dioxide, commonly featuring manganese or iron",
    "formation": "formed from weathered volcanic rock",
    "colour": "colourless with specks of white, green, blue, or brown",
    "metaphysical": [
      "gentle healing",
      "promotes tranquility",
      "cures physical ailments (inflammation, cold & flu)"
    ]
  },
  "carnelian": {
    "composition": "silicon dioxide with iron impurity",
    "formation": "formed from a combination of the silica minerals quartz and moganite",
    "colour": "orange or red often featuring yellow",
    "metaphysical": [
      "promotes life-force",
      "vitality",
      "energizes body and mind"
    ]
  },
  "spirit quartz": {
    "composition": "silicon dioxide",
    "formation": "forms when gas bubbles occur in lava and become trapped",
    "colour": "purple, yellowish brown, light grey",
    "metaphysical": [
      "assists in spiritual journey",
      "uplifts and promotes vibration"
    ]
  },
  "amazonite": {
    "composition": "potassium feldspar",
    "formation": "formed in deep sea igneous rocks that cool very slowly",
    "colour": "blue or green with white speckles or lines",
    "metaphysical": [
      "Soothes anxiety and overthinking",
      "helps heal emotional trauma"
    ]
  },
  "tourmaline": {
    "composition": "silicate of boron and aluminum",
    "formation": "Pegmatite pockets underground that slowly cool and form crystals",
    "colour": "black or pink",
    "metaphysical": [
      "repels negative energy",
      "highly protective"
    ]
  },
  "pyrite": {
    "composition": "iron sulfide",
    "formation": "forms in sedimentary rocks in low oxygen environments",
    "colour": "gold",
    "metaphysical": [
      "abundance",
      "good luck",
      "emotional strength"
    ]
  }
}

struct Response: Codable {
    let crystals: [String:Crystal]
}

struct Crystal: Codable, Identifiable {
    var id = UUID()
    let composition, formation, color: String
    let metaphysical: [String]
}

struct ContentView: View {
    @State private var crystals: [String:Crystal] = [:]
    
    var body: some View {
        List(crystals) { crystal in
            (crystal.key)
        }.onAppear(perform: loadData)
    }
    
    func loadData() {
        guard let url = URL(string: "https://lit-castle-74820.herokuapp.com/api/crystals") else { return }
        URLSession.shared.dataTask(with: url) { data, _, error in
            guard let data = data else { return }
            do {
                let decodedResponse = try JSONDecoder().decode(Response.self, from: data)
                DispatchQueue.main.async {
                  self.crystals = decodedResponse.crystals
               }
            } catch let jsonError as NSError {
              print("JSON decode failed: \(jsonError)")
            }
        }.resume()
    }
}

Answer 1

这是一个有点奇怪的API。您所面临的问题是在Crystal结构中。metaphysical似乎是一个String数组，但至少在一个例子中，它是一个简单的String。

编辑：

因为这是一个自定义API，所以您应该编辑它并返回一个String数组，即使集合中只有一个元素。

此外：

• 您的解码方法无法工作，因为JSON中没有顶级元素。这是一个[String:Crystal].
• You，在结构color -> colour

中有一个错误

然后你可以使用：

try JSONDecoder().decode([String:Crystal].self, from: data)

原件：

如果此数据是静态的(不改变)，则可以使用以下解决方案：

struct Response: Codable {
    let amethyst, mossAgate, carnelian, spiritQuartz, amazonite, tourmaline, pyrite: GemWithArray
    let clearQuartz: GemWithoutArray

    enum CodingKeys: String, CodingKey {
        case amethyst
        case clearQuartz = "clear quartz"
        case mossAgate = "moss agate"
        case carnelian
        case spiritQuartz = "spirit quartz"
        case amazonite, tourmaline, pyrite
    }
}

struct GemWithArray: Codable {
    let composition, formation, colour: String
    let metaphysical: [String]
}

struct GemWithoutArray: Codable {
    let composition, formation, colour, metaphysical: String
}

把它解码成：

try JSONDecoder().decode(Response.self, from: data)

但是有一种方法可以使它更加健壮，并且能够将它作为[String:GemWithArray]来处理。您需要在GemWithArray结构中使用自定义初始化程序。在它中，尝试将metaphysical解码到一个[String]，如果它失败了，创建一个数组，将其解码并附加为String。

struct GemWithArray: Codable {
    let composition, formation, colour: String
    let metaphysical: [String]
    
    enum CodingKeys: String, CodingKey{
        case composition, formation, colour, metaphysical
    }
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        composition = try container.decode(String.self, forKey: .composition)
        formation = try container.decode(String.self, forKey: .formation)
        colour = try container.decode(String.self, forKey: .colour)
        
        if let metaphysical = try? container.decode([String].self, forKey: .metaphysical){
            self.metaphysical = metaphysical
        } else{
            metaphysical = [try container.decode(String.self, forKey: .metaphysical)]
        }
    }
}

把它解码成：

try JSONDecoder().decode([String:GemWithArray].self, from: data)