A playground to show an example of Protocol Oriented Programming

ProtocolOrientedProgramming.swift

// MARK: - Protocols

protocol Person {
    var name: String { get }
}

protocol User {
    var identifier: String { get }
    var email: String { get }
}

extension User {
    var identifier: String { return "default value"}
}

// MARK: - Models

struct MyUser: Decodable, Person, User {
    var email: String
    var identifier: String
    var name: String
}

let json = """
{
"name": "jean",
"identifier": "identifier",
"email": "[email protected]"
}
"""

let data = json.data(using: .utf8)

if let result = try? JSONDecoder().decode(MyUser.self, from: data!) {
    dump(result)
}