Automate JSON Workflow in Swift with Codable

When you work with data in Swiftespecially when interacting with APIs, you often have to parse JSON responses and convert them into data structures. This can be a tedious and repetitive task, especially if you have complex or nested JSON structures. To solve this problem, Swift has a powerful and convenient library — Codable.

Example of use 'Codable'

Let's look at a simple examplewhere we work with the JSON response from the API containing information about the user:

{
    "id": 1,
    "name": "Phoenix Namus",
    "email": "phoenixnamus@gmail.com",
    "address": {
        "city": "Astana",
        "zipcode": "010000"
    }
}

To work with this JSON we can create the following data structures:

struct Address: Codable {
    let city: String
    let zipcode: String
}

struct User: Codable {
    let id: Int
    let name: String
    let email: String
    let address: Address
}

Now, using 'Codable', we can easily decode the JSON into a 'User' object:

let jsonData = """
{
     "id": 1,
    "name": "Phoenix Namus",
    "email": "phoenixnamus@gmail.com",
    "address": {
        "city": "Astana",
        "zipcode": "010000"
    }
}
""".data(using: .utf8)!

do {
    let user = try JSONDecoder().decode(User.self, from: jsonData)
    print(user.name)
} catch {
    print("Ошибка декодирования JSON: \(error)")
}

With 'Codable' you can also easily convert Swift objects back to JSON:

let user = User(id: 1, name: "Phoenix Namus", email: "phoenixnamus@gmail.com", address: Address(city: "Astana", zipcode: "010000"))

do {
    let jsonData = try JSONEncoder().encode(user)
    if let jsonString = String(data: jsonData, encoding: .utf8) {
        print(jsonString)
    }
} catch {
    print("Ошибка кодирования объекта в JSON: \(error)")
}

'Codable' works great with nested structures, arrays, and even custom data types, such as dates and custom types

struct User: Codable {
    let id: Int
    let fullName: String
    let email: String
    let address: Address
    
    enum CodingKeys: String, CodingKey {
        case id
        case fullName = "name"
        case email
        case address
    }
}

In this example, 'fullName' will correspond to the 'name' field in the JSON.

Using 'Codable' in Swift allows you to automate and simplify the process of working with JSON, freeing you from having to write code to parse the data manually. This makes your code cleaner, easier to maintain, and less likely to make mistakes.