Simplifying with Associated Enums in Swift

Associated enums in Swift are a nifty feature that let you attach values to each case. This adds flexibility, making enums a powerful tool in your coding toolkit.

How to Declare an Associated Enum

Here's a quick example:

enum Transportation {
    case car(licensePlate: String)
    case bicycle(brand: String, gearCount: Int)
    case airplane(model: String, passengerCapacity: Int)
}        

Using Associated Values

Create instances and access their values like this:

let myCar = Transportation.car(licensePlate: "XYZ 1234")
let myBike = Transportation.bicycle(brand: "Giant", gearCount: 21)
let myPlane = Transportation.airplane(model: "Boeing 747", passengerCapacity: 524)        

Pattern Matching

Extract values using a switch statement:

func describeTransportation(_ transport: Transportation) {
    switch transport {
    case .car(let licensePlate):
        print("Car with license plate: \(licensePlate)")
    case .bicycle(let brand, let gearCount):
        print("Bicycle: \(brand) with \(gearCount) gears")
    case .airplane(let model, let capacity):
        print("Airplane model \(model) with \(capacity) seats")
    }
}

describeTransportation(myCar)
describeTransportation(myBike)
describeTransportation(myPlane)        

Practical Use Case

Handling network responses can be streamlined with associated enums:

enum NetworkResponse {
    case success(data: Data)
    case failure(error: Error)
    case loading
}

func handleResponse(_ response: NetworkResponse) {
    switch response {
    case .success(let data):
        print("Data received: \(data)")
    case .failure(let error):
        print("Error: \(error.localizedDescription)")
    case .loading:
        print("Loading...")
    }
}

handleResponse(.loading)
handleResponse(.success(data: Data()))
handleResponse(.failure(error: NSError(domain: "NetworkError", code: 404, userInfo: nil)))        

Associated enums make your code cleaner and more expressive. Give them a try in your next project!