Question

我正在我的Swift App中解码JSON响应，并且该代码一直工作到决定停止工作为止。

这是我的json存储库

{"foods":[{"food_name":"Milk Chocolate","brand_name":"Snickers","serving_weight_grams":41.7,"nf_calories":212.3,"nf_total_fat":11.6,"nf_saturated_fat":4,"nf_total_carbohydrate":22.7,"nf_protein":3.9}]}

这是解码我的json的代码

let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
        guard let data = data else { return }

        print(String(data: data, encoding: .utf8)!)
        do {
            //Decode dataResponse received from a network request
            let decoder = JSONDecoder()
            let foods = try decoder.decode(JSONFoods.self, from: data) //Decode JSON Response Data

            self.jsonfood = foods.JSONFood[0]
            print(self.jsonfood!)

        } catch let parsingError {
            print("Error", parsingError)
        }

    }
    task.resume()

我的结构是

struct JSONFoods: Decodable {
var JSONFood: [JSONFood]    
}

struct JSONFood: Decodable{
var food_name: String
var brand_name: String
var nf_calories: Int
var nf_protein: Int
var nf_total_fat: Int
var nf_total_carbohydrate: Int
var serving_weight_grams: Int
}

我收到的错误消息是这个

keyNotFound（CodingKeys（stringValue：“ JSONFood”，intValue：nil），Swift.DecodingError.Context（codingPath：[]，debugDescription：“没有与键CodingKeys（stringValue：\” JSONFood \“，intValue：nil相关联的值））（\“ JSONFood \”）。“，underlyingError：nil））

如果我得到的是将解码（ JSONFoods .self，来自：数据）替换为解码（ JSONFood .self，来自：数据）我收到此错误消息

keyNotFound（CodingKeys（stringValue：“ food_name”，intValue：nil），Swift.DecodingError.Context（codingPath：[]，debugDescription：“没有与键CodingKeys相关联的值（stringValue：\” food_name \“，intValue：nil ）（\“ food_name \”）。“，underlyingError：nil））

我到处搜索都没有运气，非常感谢

Answer 1

您需要

struct Root: Codable {
    let foods: [Food]
}

struct Food: Codable {
    let foodName: String?
    let  brandName: String
    let servingWeightGrams, nfCalories, nfTotalFat: Double
    let nfSaturatedFat: Int
    let nfTotalCarbohydrate, nfProtein: Double

    enum CodingKeys: String, CodingKey {
        case foodName = "food_name"
        case brandName = "brand_name"
        case servingWeightGrams = "serving_weight_grams"
        case nfCalories = "nf_calories"
        case nfTotalFat = "nf_total_fat"
        case nfSaturatedFat = "nf_saturated_fat"
        case nfTotalCarbohydrate = "nf_total_carbohydrate"
        case nfProtein = "nf_protein"
    }
}

首先：，您制作的JSONFood应该是foods

第二个： food_name在当前json根目录中不存在，因此将失败

let foods = try decoder.decode(JSONFoods.self, from: data) //Decode JSON Response Data

以防利用convertFromSnakeCase

let str = """

{"foods":[{"food_name":"Milk Chocolate","brand_name":"Snickers","serving_weight_grams":41.7,"nf_calories":212.3,"nf_total_fat":11.6,"nf_saturated_fat":4,"nf_total_carbohydrate":22.7,"nf_protein":3.9}]}

"""

    do {
        let res = JSONDecoder()
        res.keyDecodingStrategy = .convertFromSnakeCase
        let ss = try res.decode(Root.self, from:Data(str.utf8))
        print(ss)
    }
    catch {
        print(error)
    }

struct Root: Codable {
    let foods: [Food]
}

struct Food: Codable {
    let foodName: String?
    let  brandName: String
    let servingWeightGrams, nfCalories, nfTotalFat: Double
    let nfSaturatedFat: Int
    let nfTotalCarbohydrate, nfProtein: Double
}

Swift 4 Decodable-与CodingKeys键无关的值

1 个答案: