Turn Codable data into a `[String: CustomStringConvertible]` dictionary

Question

This is similar to for example this question: How can I use Swift’s Codable to encode into a dictionary?, except that I want to specifically turn it into a [String: CustomStringConvertible] dictionary and I am not able to.

struct Model: Codable {
  let a: String
  let b: Int
}

let jsonData = try JSONEncoder().encode(Model(a: "a", b: 1))
let parameters = try JSONSerialization.jsonObject(with: jsonData, options: .allowFragments)
parameters as? [String: CustomStringConvertible] // nil

How can I make this work? This for example does work, which should work the same you'd think:

let dict: Any = ["a": "a", "b": 1]
dict as? [String: CustomStringConvertible] // ["a": "a", "b": 1]

Because I need these dictionaries to be Equatable, which `[String: CustomStringConvertible]` is super handy for. And they fit the kind of data I'm working with, so win win :) — Kevin Renskers, Oct 13 '21 at 13:57
Wouldn't it be easier to compare objects for equality instead of comparing dictionaries? `CustomStringConvertible` is maybe handy but it won't give always correct results. Sounds a bit like a javascripty solution. — Sulthan, Oct 13 '21 at 14:01
Is that really a win win? 1 and "1" will be considered equal which isn't exactly true and a custom type (as value) that conforms to both Equatable and CustomStringConvertible will be compared using the latter protocol — Joakim Danielson, Oct 13 '21 at 14:12
It's for HTTP endpoint parameters where it doesn't matter if we compare "1" and 1, and yeah there's a reason for all of this, which is hard to explain in just a simple SO question. — Kevin Renskers, Oct 15 '21 at 12:13

Kevin Renskers · Answer 1 · 2021-10-13T13:56:39.010

0

The trick is to first cast it to [String: AnyObject] and THEN to [String: CustomStringConvertible]:

struct Model: Codable {
  let a: String
  let b: Int
}

let jsonData = try JSONEncoder().encode(Model(a: "a", b: 1))
let parameters = try JSONSerialization.jsonObject(with: jsonData, options: .allowFragments) as? [String: AnyObject] as? [String: CustomStringConvertible]

Weird, but it works ‍♂️

edited Oct 13 '21 at 13:56

answered Oct 13 '21 at 11:09

Kevin Renskers

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Turn Codable data into a `[String: CustomStringConvertible]` dictionary

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