The Advanced Swift Feature: Codable

Swift is a powerful and versatile programming language that can be used for a variety of purposes, including server-side development. In this tutorial, we will explore one of the latest additions to Swift's feature set that has made server-side development much easier and more convenient: Codable.

What is Codable?

Codable is a protocol that was introduced in Swift 4. It allows you to easily encode and decode data types to and from binary or JSON data format.

Codable protocol requires that the model you want to encode or decode must incorporate two handy protocols: Encodable and Decodable. The Encodable protocol is used when you want to encode or serialize data to a JSON or binary format. On the other hand, the Decodable protocol is used when you want to decode or deserialize data from a JSON or binary format.

Encoding and Decoding Data using Codable Protocol

Let's say you want to encode a struct to JSON data. Here is how you can implement it using Codable:

struct Employee: Codable {
  let name: String
  let age: Int
  let email: String
}

let employee = Employee(name: "Jane Doe", age: 30, email: "jane.doe@example.com")
let jsonEncoder = JSONEncoder()

do {
  let jsonData = try jsonEncoder.encode(employee)
  let jsonString = String(data: jsonData, encoding: .utf8)!
  print(jsonString)
} catch {
  print("Error encoding employee: \(error.localizedDescription)")
}

In the above code, we first define the Employee struct, which incorporates the Codable protocol. Next, we create an instance of the Employee struct and set the values of its properties. Then we create an instance of the JSONEncoder class, which is responsible for encoding data to JSON format.

Finally, we pass the Employee instance to the JSONEncoder's encode method to get the encoded JSON data. Finally, we convert the JSON data to a string, so we can print it on the console for debugging purposes.

You can also decode JSON data using the Codable protocol. Here is the code snippet for decoding JSON data:

let jsonString = """
  {"name": "Jane Doe", "age": 30, "email": "jane.doe@example.com"}
"""
let jsonData = jsonString.data(using: .utf8)!
let jsonDecoder = JSONDecoder()

do {
  let employee = try jsonDecoder.decode(Employee.self, from: jsonData)
  print(employee)
} catch {
  print("Error decoding employee: \(error.localizedDescription)")
}

In the above code, we first define a JSON string, which we will decode using the JSONDecoder class. We then convert the JSON string to JSON data, so it can be easily decoded by JSONDecoder.

Finally, we pass the JSON data to the JSONDecoder's decode method and pass the Employee struct type as the first parameter, so JSONDecoder knows which data type it should decode. Finally, we print the employee object on the console for debugging purposes.

Conclusion

Codable protocol has made it much easier to encode and decode data types to and from binary or JSON data format. It's a powerful feature added to Swift that has made server-side development much easier and more convenient.