快速过滤json数组

Question

如何快速过滤只有某些键值对的 json 数组？

我的数组看起来像：

[{
  "status" : "true",
  "score" : "3",
  "correct" : "3",
  "chapter" : "34",
  "answer" : "342432",
  "solutionText" : "abcd",
}, {

  "status" : "true",
  "score" : "0",
  "correct" : "2",
  "chapter" : "35",
  "answer" : "35854",
  "solutionText" : "abc",

}]

我想得到一个只有 status、chapter 和 correct 键值对的 json 输出数组。

喜欢：

[{
  "status" : "true",
  "correct" : "3",
  "chapter" : "34",
}, {

  "status" : "true",
  "correct" : "2",
  "chapter" : "35",
}]

Answer 1

考虑到这是您的JSON

var myJSON = """
[{
    "status" : "true",
    "score" : "3",
    "correct" : "3",
    "chapter" : "34",
    "answer" : "342432",
    "solutionText" : "abcd"
    }, {

        "status" : "true",
        "score" : "0",
        "correct" : "2",
        "chapter" : "35",
        "answer" : "35854",
        "solutionText" : "abc"

    }]
"""

像这样简单地创建一个Decodable struct

typealias  MyArray = [MyObject] // Use this to decode 

struct MyObject: Codable {
    let status, correct, chapter: String
}

并像这样使用它

//Usage
var myJSONData = myJSON.data(using: .utf8)! // converting the JSON to data 
let objArray = try! JSONDecoder().decode(MyArray.self, from: myJSONData) // decoding the json data into an object


   //how to access
print(objArray.count)// number of elements in my array
print(objArray.first!) // getting the first object
 let myObject =  obj[0] // also getting the first object by index
 myObject.chapter
 myObject.correct
 myObject.status

了解Codable here。

Answer 2

如果它已经在一个对象中，你可以试试

filteredArray = myArray.map { ["status": $0.status, "correct": $0.correct, "chapter": $0.chapter]  }

Answer 3

你可以试试

do {
    
    let res = try JSONDecoder().decode([Root].self, from:data)
 
}
catch {
    
    print(error)
}

---

struct Root: Codable {
  let status, correct, chapter: String
}

正确的json

[{
    "status" : "true",
    "score" : "3",
    "correct" : "3",
    "chapter" : "34",
    "answer" : "342432",
    "solutionText" : "abcd"
    }, {
        
        "status" : "true",
        "score" : "0",
        "correct" : "2",
        "chapter" : "35",
        "answer" : "35854",
        "solutionText" : "abc"
        
}]

更适合做

状态是布尔值而不是字符串

正确&章节为整数

所以 json 看起来像

[{
    "status" : true,
    "score" : "3",
    "correct" : 3,
    "chapter" : 34,
    "answer" : "342432",
    "solutionText" : "abcd"
    }, {
        
        "status" : true,
        "score" : "0",
        "correct" : 2,
        "chapter" : 35,
        "answer" : "35854",
        "solutionText" : "abc"
        
}]

如果需要，您还可以设置其他类似的值，那么您的模型将如下所示

struct Root: Codable {
  let status: Bool
  let correct, chapter: Int
}

编辑：

let data = try content.rawData() // this inside do block

其中content 的类型为JSON

Answer 4

试试Decodable的swift

class MyObjectsClass : Decodable {
   var objects : [Objects]?
}

class Objects : Decodable {
   var status : String?
   var correct : String?
   var chapter : String?
}

解码时

let decodedValue = try? JSONDecoder.decode(MyObjectsClass.self, from : data)
// where data from API calls