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json - 尝试通过 jsondecoder 解码 json 时出错

问题描述

这是我的 json，我正在尝试使用 JSONDecoder 进行解码，但由于无法做到这一点而遇到了困难。有人可以帮助什么结构，我该如何解码？

{
"Afghanistan": [
    {
        "city": "Kabul",
        "lat": "34.5167",
        "lng": "69.1833",
        "state": "Kābul",
        "country": "Afghanistan"
    },
    {
        "city": "Karukh",
        "lat": "34.4868",
        "lng": "62.5918",
        "state": "Herāt",
        "country": "Afghanistan"
    },
    {
        "city": "Zarghūn Shahr",
        "lat": "32.85",
        "lng": "68.4167",
        "state": "Paktīkā",
        "country": "Afghanistan"
    }
],
"Albania": [
    {
        "city": "Tirana",
        "lat": "41.3275",
        "lng": "19.8189",
        "state": "Tiranë",
        "country": "Albania"
    },

    {
        "city": "Pukë",
        "lat": "42.0333",
        "lng": "19.8833",
        "state": "Shkodër",
        "country": "Albania"
    }
]}

你有什么建议解码它？

我正在尝试这个

let locationData: Countries = load("Countries.json")

func load<T: Decodable>(_ filename: String) -> T {
let data: Data

guard let file = Bundle.main.url(forResource: filename, withExtension: nil)
else {
    fatalError("Couldn't find \(filename) in main bundle.")
}

do {
    data = try Data(contentsOf: file)
} catch {
    fatalError("Couldn't load \(filename) from main bundle:\n\(error)")
}

do {
    let decoder = JSONDecoder()
    return try decoder.decode(T.self, from: data)
} catch {
    fatalError("Couldn't parse \(filename) as \(T.self):\n\(error)")
}
 }

struct Country: Codable, Identifiable {
var id = UUID()

let city, lat, lng: String
let state: String?
let country: String
}

typealias Countries = [String: [Country]]

但是得到这个错误

无法将 Country.json 解析为 Dictionary>: keyNotFound(CodingKeys(stringValue: "id", intValue: nil), Swift.DecodingError.Context(codingPath: [_JSONKey(stringValue: "Albania", intValue: nil), _JSONKey( stringValue: "Index 0", intValue: 0)], debugDescription: "No value associated with key CodingKeys(stringValue: \"id\", intValue: nil) (\"id\").", underlyingError: nil)) ：

标签： jsonswiftswift5codable

解决方案

由于该属性id不是 json 的一部分，因此您需要通过添加 CodingKey 枚举来定义解码器应解码的属性Country

enum CodingKeys: String, CodingKey {
    case city, lat, lng, state, country
}

CodingKey 枚举还使您有机会为您的结构属性使用更好的名称，并将它们在枚举中映射到 json 键。

struct Country: Codable, Identifiable {
    var id = UUID()

    let city: String
    let latitude: String
    let longitude: String
    let state: String?
    let country: String

    enum CodingKeys: String, CodingKey {
        case city
        case latitude = "lat"
        case longitude = "lng"
        case state, country
    }
}

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