Why is decoded json nil using Codable? - json

Question

I'm using latest version of Swift with xcode 10.1. I'm able to encode json from an object fine but decoding a json string back to an object is producing nil.
This is from a hacker noon tutorial and the tutorial source prints nil as well.
Here is the sample object:
class Car: NSObject, Codable {
var name: String = ""
var companyURL: URL? = nil
var yearOfManufacture: Int = 0
var isNew:Bool = true
var otherDetailsData: [String:String]? = nil
var carType: CarType = .Unknown
var carSize: CarSize = CarSize(height: 0, length: 0)
}
struct CarSize: Codable {
var height: Double
var length: Double
}
enum CarType: String, Codable {
case Unknown
case SUV
case Sedan
}
//here is sample json
let jsonString = """
{
"name":"City ZX",
"isNew":true,
"yearOfManufacture":2018,
"companyURL":"www.honda.com",
"carType":"Sedan",
"carSize":{
"height":200,
"height":100
},
"otherDetailsData":{
"color":"Red",
"fuelType":"Petrol"
},
}
"""
//here is where i attempt to create the object from the json string:
if let jsonData = jsonString.data(using: .utf8)
{
//And here you get the Car object back
let carTest = try? JSONDecoder().decode(Car.self, from: jsonData)
print("carObject currently printing nil ", carTest)
}

Answer 1

Your CarSize struct has properites height and length, but in your jsonString you declared just height twice, so you forgot to length which is required for decoding too.
You probably wanted to use length instead of second height in your jsonString
"carSize":{
"height":200,
"length":100
}
or (if your car isn't skyscraper)
"carSize":{
"height":100,
"length":200
}