filter array of json in swift - ios

Question

How can i filter an array of json in swift having only certain key value pairs?
my array looks like:
[{
"status" : "true",
"score" : "3",
"correct" : "3",
"chapter" : "34",
"answer" : "342432",
"solutionText" : "abcd",
}, {
"status" : "true",
"score" : "0",
"correct" : "2",
"chapter" : "35",
"answer" : "35854",
"solutionText" : "abc",
}]
i want to get an array of json output having only status, chapter & correct key value pairs.
Like:
[{
"status" : "true",
"correct" : "3",
"chapter" : "34",
}, {
"status" : "true",
"correct" : "2",
"chapter" : "35",
}]

Answer 1

Considering this is your 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"
}]
"""
Simply create a Decodable struct like this
typealias MyArray = [MyObject] // Use this to decode
struct MyObject: Codable {
let status, correct, chapter: String
}
And use it like this
//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
Read about Codable here .

Answer 2

If it's already in an object, you can try
filteredArray = myArray.map { ["status": $0.status, "correct": $0.correct, "chapter": $0.chapter] }

Answer 3

You can try
do {
let res = try JSONDecoder().decode([Root].self, from:data)
}
catch {
print(error)
}
struct Root: Codable {
let status, correct, chapter: String
}
Correct 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"
}]
It's more suitable to make
status a bool not string
correct & chapter to be integers
so json look like
[{
"status" : true,
"score" : "3",
"correct" : 3,
"chapter" : 34,
"answer" : "342432",
"solutionText" : "abcd"
}, {
"status" : true,
"score" : "0",
"correct" : 2,
"chapter" : 35,
"answer" : "35854",
"solutionText" : "abc"
}]
you can also make other values like that if you need , then your model will look like
struct Root: Codable {
let status: Bool
let correct, chapter: Int
}
Edit:
let data = try content.rawData() // this inside do block
where content is of type JSON

Answer 4

try Decodable of swift
class MyObjectsClass : Decodable {
var objects : [Objects]?
}
class Objects : Decodable {
var status : String?
var correct : String?
var chapter : String?
}
While Decoding
let decodedValue = try? JSONDecoder.decode(MyObjectsClass.self, from : data)
// where data from API calls