[Swift] namespacing for better domain management

[vinhnx]

Say we want write custom logic for a specific domain. For example: below, I have a UUID getter and setter.

We could add a nested enum/struct for AppUUID.

import KeychainAccess

final class KeychainHelper {
    
    // MARK: - Public
    
    static func nxv_store(_ value: String, key: String) {
        let keychain = Keychain(service: "\(AppConfiguration.App.bundleID).\(key)")
        keychain[key] = value
    }
    
    static func nxv_valueForKey(_ key: String) -> String {
        let keychain = Keychain(service: "\(AppConfiguration.App.bundleID).\(key)")
        return keychain[key] ?? ""
    }
}

extension KeychainHelper {
    
    // MARK: - UUID
    
    struct AppUUID {
        static func generateAppUUIDandStore() {
            // only generate and store UUID on when we can't get UUID from keychain,
            // since we store it to keychain, so don't check for first launch
            if isAppUUIDValid == false {
                KeychainHelper.nxv_store(UUID().uuidString, key: Constants.Keychain.savedAppUUID)
            }
        }
        
        static var appUUID: String {
            return KeychainHelper.nxv_valueForKey(Constants.Keychain.savedAppUUID)
        }
        
        static var isAppUUIDValid: Bool {
            return appUUID.isEmpty == false
        }
    }
}

So in usage, it's better to know on glance which problem we are dealing from the helper

let appUUID = KeychainHelper.AppUUID.appUUID

// is, in my opinion, better than

let appUUID = KeychainHelper.appUUID

As we glance it, we could see that we are telling KeychainHelper, return me a generated appUUID from AppUUID domain.

We could just declare struct UUID, but thanks to Swift compiler warning, in the setter, we use Foundation's UUID class method UUIDString to generate a unique ID. So namespace collision happened there.

TIL