Swift and JSON UUID - Write to var and read from the var the id's are different

Question

I did wrote some code to save some struct to disk in JSON format. However, if I save it in a variable and keep that and use it to decoded it then the UUID's are different.

import Foundation
import PlaygroundSupport
import Swift

struct Project: Codable, Identifiable, Hashable  {
    let id: UUID = UUID()
    let id2: String = UUID().uuidString 
    let name: String
}

let project = Project(name: "PP50")
let encodedData = try JSONEncoder().encode(project)
let jsonString = String(data: encodedData,
                        encoding: .utf8)

print(project.id)
print(project.id2)
print(project.name)
print(jsonString)
print("===================")

if let dataFromJsonString = jsonString?.data(using: .utf8) {
    let projectFromData = try JSONDecoder().decode(Project.self, from: dataFromJsonString)
    print(projectFromData)
    print(projectFromData.name)
    print(projectFromData.id) // <<< why is the id and id'2 different
    print(projectFromData.id2)
}

The result is:

826FEC8A-7FE0-4E6C-8DC1-A0DFA4FC75BE
2D15A1B8-B936-4829-8DC2-9C44B261712E
PP50
Optional("{\"id\":\"826FEC8A-7FE0-4E6C-8DC1-A0DFA4FC75BE\",\"id2\":\"2D15A1B8-B936-4829-8DC2-9C44B261712E\",\"name\":\"PP50\"}")
===================
Project(id: E951D459-3C0E-43A3-B9C6-2CCF2EB1AEE3, id2: "3C97B5C3-054D-4372-800D-9210439F48C2", name: "PP50")
PP50
E951D459-3C0E-43A3-B9C6-2CCF2EB1AEE3
3C97B5C3-054D-4372-800D-9210439F48C2

Maybe a simple answer, but I don't see it yet. Why is the outcome of the id different then the one created? How come? How to solve this?

Answer 1

All you need to do is to var declare your id properties and they will be included in the decoding

var id: UUID = UUID()
var id2: String = UUID().uuidString