URL namespace to collect URLs in a convenient place.

URL+Namespace.swift

extension URL {
    enum MyURLNamespace {
        // Static URL, always in memory
        static let gitHub = URL(string: "https://github.com/BjornRuud")!

        // Computed URL, created on demand
        static var gitHubWithStaticParameter: URL {
            let param = "SomeParameter"
            return URL(string: "https://github.com/BjornRuud/\(param)")!
        }

        // Computed URL with parameters
        static func gitHubHome(userID: String) -> URL {
            return URL(string: "https://github.com/\(userID)")!
        }
    }

    static let mynamespace = MyURLNamespace.self
}

// Usage:
let url = URL.mynamespace.gitHub