可编码错误 - 预期解码字典<字符串、任何>但找到了一个数组

Question

我正在尝试在可编码的帮助下解码JSON - https://pastebin.com/Xfjj2XiP

但是，当我这样做时，我会收到此错误。

typeMismatch(Swift.Dictionary<Swift.String，>，

Swift.DecodingError.Context(codingPath： [CodingKeys(stringValue： "txt_forecast"， intValue： nil(]， debugDescription： "预期解码 Dictionary<String，> 但找到了一个数组。

这是我使用的代码：

struct container: Decodable {
var days: [forecastDay]
//Coding keys
enum CodingKeys: String, CodingKey {
case forecast = "forecast"
case txt_forecast = "txt_forecast"
case forecastday = "forecastday"
}
// Decoding
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
let forecast = try container.nestedContainer(keyedBy: CodingKeys.self, forKey: .forecast)
let txt_forecast = try forecast.nestedContainer(keyedBy: CodingKeys.self, forKey: .txt_forecast)
let forecastdays = try txt_forecast.nestedContainer(keyedBy: CodingKeys.self, forKey: .forecastday)
let forecastdaysData = try forecastdays.decode(String.self, forKey: .forecastday)
days = try JSONDecoder().decode([forecastDay].self, from: forecastdaysData.data(using: .utf8)!)
print(days)
}
}
struct forecastDay: Decodable {
var period: Int?
var icon: String?
var title: String?
var fcttext: String?
//Coding keys
enum CodingKeys: String, CodingKey {
case period = "period"
case icon = "icon"
case title = "title"
case fcttext = "fcttext"
}
// Decoding
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
period = try container.decode(Int.self, forKey: .period)
icon = try container.decode(String.self, forKey: .icon)
title = try container.decode(String.self, forKey: .title)
fcttext = try container.decode(String.self, forKey: .fcttext)
}
}

Answer 1

forecastDay中的变量名称与 JSON 中的键没有区别，init(from decoder:)也不执行任何自定义操作，因此可以简化预测日期间的结构。

struct ForecastDayPeriod: Decodable {
let period: Int
let icon: String
let title: String
let fcttext: String
}

现在，最好对 JSON 中的每个级别使用带有键的枚举。另外，init(from decoder:)不应该创建一个新的JSONDecoder。

struct ForecastDay: Decodable {
let periods: [ForecastDayPeriod]
enum CodingKeys: String, CodingKey {
case forecast
}
enum ForecastKeys: String, CodingKey {
case txtForecast = "txt_forecast"
}
enum TxtForecastKeys: String, CodingKey {
case forecastday
}
init(from decoder: Decoder) throws {
let values = try decoder.container(keyedBy: CodingKeys.self)
let forecast = try values.nestedContainer(keyedBy: ForecastKeys.self,
forKey: .forecast)
let txtForecast = try forecast.nestedContainer(keyedBy: TxtForecastKeys.self,
forKey: .txtForecast)
periods = try txtForecast.decode([ForecastDayPeriod].self,
forKey: .forecastday)        
}
}

现在应该可以从 pastebin 示例中解码 JSON。

do {
let jsonData: Data = ...
let forecastDay = try JSONDecoder().decode(ForecastDay.self, from: jsonData)
} catch {
print("Error: (error)")
}