JSON in Swift - the way it should be.

• iOS 9.0+ / macOS 10.9+ / tvOS 9.0+ / watchOS 2.0+
• Xcode 10.2+
• Swift 5.0+

In the modern era of Codable it is rare that we need to handle JSON data manually. Nevertheless there are times when we can't know the structure in advance, but we can still utilise Codable to make our lives easier.

For example, when loading JSON data:

{
  "Apple": {
    "address": {
      "street": "1 Infinite Loop",
      "city": "Cupertino",
      "state": "CA",
      "zip": "95014"
    },
    "employees": 132000
  }
}

You would have had to perform a lot of casting to get the inner values.

guard let companies = try JSONSerialization.jsonObject(with: companiesData) as? [String: Any] else { return }

if let company = companies["Apple"] as? [String: Any],
    let address = company["address"] as? [String: Any],
    let city = address["city"] as? String {
    print("Apple is in \(city)")
}

Changing the inner values would also involve several castings.

guard var companies = try JSONSerialization.jsonObject(with: companiesData) as? [String: Any] else { return }

if var apple = companies["Apple"] as? [String: Any],
    var address = apple["address"] as? [String: Any] {
    address["state"] = "California"
    apple["address"] = address
    companies["Apple"] = apple
}

Since JSON has a fixed set of types there's no need to perform all these casts in long form. CodableJSON uses an enum to store each type. With the aid of some helper functions, accessing the JSON values is now significantly shorter and easier.

let companies = try JSONDecoder().decode(JSON.self, from: companiesData)

if let city = companies["Apple"]?["address"]?["city"]?.stringValue {
    print("Apple is in \(city)")
}

You can even use mutable forms in order to change the inner values. E.g. You could change the state to its full name:

var companies = try JSONDecoder().decode(JSON.self, from: companiesData)

companies["Apple"]?["address"]?["state"] = "California"

pod 'CodableJSON'

github "guykogus/CodableJSON"

import PackageDescription

let package = Package(
    name: "YOUR_PROJECT_NAME",
    targets: [],
    dependencies: [
        .package(url: "https://github.com/guykogus/CodableJSON.git", from: "1.2.0")
    ]
)

.target(
    name: "YOUR_TARGET_NAME",
    dependencies: [
        "CodableJSON",
    ]
),

CodableJSON is available under the MIT license. See the LICENSE file for more info.