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iOS Parsing JSON Using Codable An Overview of Codable The Decodable Protocol

Christian A. Castro
Christian A. Castro
30,501 Points

Any idea why I'm receiving this error message in the console!!! Initialization of immutable value 'container', Help!

Error message: Initialization of immutable value 'container' was never used; consider replacing with assignment to '_' or removing it let container = try decoder.container(keyedBy: CodingKeys.self)

import Foundation

let json = """
{
    "name": "Pasan",
    "id": 1,
    "role": "Teacher"
}

//Conversting string literal into a data object with utf8
""".data(using: .utf8)!

struct Employee: Codable
{
    let name: String
    let id: Int
    let role: String

    enum CodingKeys: String, CodingKey
    {
        //Providing a raw value
        case name = "name"
        case id = "id"
        case role = "role"

    }

    init (from decoder: Decoder) throws
    {
        let container = try decoder.container(keyedBy: CodingKeys.self)



        self.name = try container.decode(String.self, forKey: .name)
        self.id = try container.decode(Int.self, forKey: .id)
        self.role = try container.decode(String.self, forKey: .role)

    }
}

//We need a decoder to handle decoding the JSON, parsing it and assigning values.
let decoder = JSONDecoder()

//Creating an instance of JSONDecoder
let employee = try! decoder.decode(Employee.self, from: json)

employee.name
employee.role

2 Answers

I tried your code and did not receive that warning. Cmd Q and restart the playground.

Your comment "//Conversting string literal into a data object with utf8" is inside the json String, so it's not valid JSON.