Articles, podcasts and news about Swift development, by John Sundell.

Creating a dedicated identifier type

Published on 07 May 2018
Basics article available: Protocols

If you want to avoid using plain strings as identifiers (which can increase both type safety and readability), it's really easy to create a custom Identifier type that feels just like a native Swift type, thanks to protocols!

struct Identifier: Hashable {
    let string: String
}

extension Identifier: ExpressibleByStringLiteral {
    init(stringLiteral value: String) {
        string = value
    }
}

extension Identifier: CustomStringConvertible {
    var description: String {
        return string
    }
}

extension Identifier: Codable {
    init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        string = try container.decode(String.self)
    }

    func encode(to encoder: Encoder) throws {
        var container = encoder.singleValueContainer()
        try container.encode(string)
    }
}

struct Article: Codable {
    let id: Identifier
    let title: String
}

let article = Article(id: "my-article", title: "Hello world!")

Support Swift by Sundell by checking out this sponsor:

Raycast

Raycast: Take the macOS Spotlight experience to the next level: Create Jira issues, manage GitHub pull requests and control other tools with a few keystrokes. Easily automate every-day tasks and boost your developer productivity by downloading Raycast for free.