What's the best practice for naming Swift files that add extensions to existing objects?

Question

It\'s possible to add extensions to existing Swift object types using extensions, as described in the language specification.

As a result, it\'s possible to create exten

Answer 1

If you have a team-agreed set of common and miscellaneous enhancements, lumping them together as an Extensions.swift works as Keep-It-Simple first level solution. However, as your complexity grows, or the extensions become more involved, a hierarchy is needed to encapsulate the complexity. In such circumstances I recommend the following practice with an example.

I had a class which talks to my back-end, called Server. It started to grow bigger to cover two different target apps. Some people like a large file but just logically split up with extensions. My preference is to keep each file relatively short so I chose the following solution. Server originally conformed to CloudAdapterProtocol and implemented all its methods. What I did was to turn the protocol into a hierarchy, by making it refer to subordinate protocols:

protocol CloudAdapterProtocol: ReggyCloudProtocol, ProReggyCloudProtocol {
    var server: CloudServer {
        get set
    }
    func getServerApiVersion(handler: @escaping (String?, Error?) -> Swift.Void)
}

In Server.swift I have

import Foundation
import UIKit
import Alamofire
import AlamofireImage

class Server: CloudAdapterProtocol {
.
.
func getServerApiVersion(handler: @escaping (String?, Error?) -> Swift.Void) {
.
.
}

Server.swift then just implements the core server API for setting the server and getting the API version. The real work is split into two files:

Server_ReggyCloudProtocol.swift
Server_ProReggyCloudProtocol.swift

These implement the respective protocols.

It means you need to have import declarations in the other files (for Alamofire in this example) but its a clean solution in terms of segregating interfaces in my view.

I think this approach works equally well with externally specified classes as well as your own.