Example code in Swift 4.1 for JSON using the Codable protocol

swift-4.1-Codable-JSON.swift

#!/usr/bin/swift

// swift-4.1-Codable-JSON.swift
// 
// Example code in Swift 4.1 for JSON using the Codable protocol

import Foundation

let encoder = JSONEncoder()
let decoder = JSONDecoder()

struct Person : Codable {
    var name = "Taylor"
}

let peopleOut = [Person()]
print("Original: \(peopleOut)")

guard let dataOut = try? encoder.encode(peopleOut) else {
    fatalError("Failed to encode the object.")
}
guard let stringEncoded = String(data: dataOut, encoding: .utf8) else {
    fatalError("Failed to convert the data to a String.")
}
print("Encoded:            \(stringEncoded)")

guard let dataIn = stringEncoded.data(using: .utf8, allowLossyConversion: false) else {
    fatalError("Failed to convert the encoded string to data.")
}
guard let peopleIn = try? decoder.decode([Person].self, from: dataIn) else {
    fatalError("Failed to decode the data.")
}
print("Decoded:  \(peopleIn))")


// after Paul Hudson's
// What’s new in Swift 4.1
// https://www.hackingwithswift.com/articles/50/whats-new-in-swift-4-1

// 2018-02-11 Output with the Xcode 9.3 beta2 swift toolchain
//   Original: [main.Person(name: "Taylor")]
//   Encoded:            [{"name":"Taylor"}]
//   Decoded:  [main.Person(name: "Taylor")])

// The trailing ) was actually in the output.