How to extract and make specific arrays from JSON in Swift 4? - ios

Question

I am very new in swift and trying to extract information from a Json response and save them in some separate arrays.
Here is my Json:
{
"result": {
"date": [
{
"TestDate": 970606
},
{
"TestDate": 980703
}
],
"headId": [
{
"AreaCode": 200,
"AreaName": "center"
},
{
"AreaCode": 300,
"AreaName": "Middle"
}
]
}
}
I want to have an array for AreaName and another array for TestDate.
Can you please tell me how to do this?

Answer 1

You decode the JSON with Decodable and then pick off the pieces you want from it:
import Foundation
struct Response: Decodable {
struct Result: Codable {
let headID: [HeadID]
let date: [DateElement]
enum CodingKeys: String, CodingKey {
case headID = "headId"
case date
}
}
struct DateElement: Codable {
let testDate: Int
enum CodingKeys: String, CodingKey {
case testDate = "TestDate"
}
}
struct HeadID: Codable {
let areaCode: Int
let areaName: String
enum CodingKeys: String, CodingKey {
case areaCode = "AreaCode"
case areaName = "AreaName"
}
}
let result: Result
}
let data = """
{
"result": {
"headId": [
{
"AreaCode": 200,
"AreaName": "center"
},
{
"AreaCode": 300,
"AreaName": "Middle"
}
],
"date": [
{
"TestDate": 970606
},
{
"TestDate": 980703
}
]
}
}
""".data(using: .utf8)!
let response = try JSONDecoder().decode(Response.self, from: data)
let areaNames = response.result.headID.map { $0.areaName }
let testDates = response.result.date.map { $0.testDate }
print(areaNames)
print(testDates)

Answer 2

What I use that saves me a lot of time is a website that will translate the JSON structure to Swift for me. https://app.quicktype.io/
It's super duper helpful, and usually works perfectly just by copying and pasting the structures and classes into my Swift file.