Identifiable protocol in swiftUI... id property... var vs let

Question

In the Landmarks tutorial for SwuiftUI by Apple, is there some reason why the id property of the Landmarks struct is a var and not a let?

import SwiftUI
import CoreLocation

struct Landmark: Hashable, Codable, Identifiable {
    var id: Int 

// ...
}

Answer 1

Apparently not. You can safely turn the id into a let and all will work fine.

In fact, the Identifiable protocol has no conflict there. It only requires id to be gettable. It says nothing about settable:

public protocol Identifiable {

    /// A type representing the stable identity of the entity associated with `self`.
    associatedtype ID : Hashable

    /// The stable identity of the entity associated with `self`.
    var id: Self.ID { get }
}