Swift解析Json

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Swift解析Json

使用

Json文件

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{
  "startCursor": "0",
  "endCursor": "0",
  "list": [
    {
      "id": 195524,
      "name": "测试1",
      "paid": true
    },
    {
      "id": 195508,
      "name": "测试2",
      "paid": true
    }
  ]
}

结构体

结构体
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struct LessonListItem: Codable {
    let id: Int64
    let name: String
    let paid: Bool
}

解析Json文件

解析Json文件
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//要获取文件中“list”下的数据，需要手动创建一个结构体
struct CardList: Codable {
    let list: [LessonListItem]	//在decode时会把“list”对应的数据返回到该属性上
}

func loadJson(filename fileName: String) -> [LessonListItem]? {
    if let url = Bundle.main.url(forResource: fileName, withExtension: "json") {
        do {
            let data = try Data(contentsOf: url)
            let jsonData = try JSONDecoder().decode(CardList.self, from: data)
            return jsonData.list
        } catch {
            print("error:\(error)")
        }
    }
    return nil
}

为属性选择可选的keys

为属性选择可选的keys
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struct Landmark: Codable {
    var name: String
    var foundingYear: Int

    enum CodingKeys: String, CodingKey {
        case name = "title"	//json中的“title”数据也能映射到name上
        case foundingYear = "founding_date"
    }
}

映射不同level的数据

映射不同level的数据
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//json中的数据：
"latitude":
"additionalInfo":
		"elevation":
//结构体中的数据：
"latitude":
"additionalInfo":
"elevation":

struct Coordinate {
    var latitude: Double
    var elevation: Double

    //第一级的key
    enum CodingKeys: String, CodingKey {
        case latitude
        case additionalInfo
    }

  	//第二级的key
    enum v: String, CodingKey {
        case elevation
    }
}
//实现decode
extension Coordinate: Decodable {
    init(from decoder: Decoder) throws {
      	//获取第一级的映射集
        let values = try decoder.container(keyedBy: CodingKeys.self)
        latitude = try values.decode(Double.self, forKey: .latitude)
        //获取第二级的映射集
      	let additionalInfo = try values.nestedContainer(
          	keyedBy: AdditionalInfoKeys.self, 
          	forKey: .additionalInfo
        )
        elevation = try additionalInfo.decode(Double.self, forKey: .elevation)
    }
}
//实现encode
extension Coordinate: Encodable {
    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(latitude, forKey: .latitude)
        
      	var additionalInfo = container.nestedContainer(
          	keyedBy: AdditionalInfoKeys.self, 
          	forKey: .additionalInfo
        )
        try additionalInfo.encode(elevation, forKey: .elevation)
    }
}
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