import UIKit

struct Model {

    private init() {}
}

extension Model {

    static let defaultName = "anyone"
    static let defaultPassword = "Awesome"
    struct Account {
        let username: String
        let password: String
    }
}

struct API {

    private init() {}
}

extension API {

    struct Account {

        static func getFromServer() -> Model.Account {
            // Do something here
            return Model.Account(username: Model.defaultName, password: Model.defaultPassword)
        }
    }
}

// How to use
struct DoSomething {
    var account: Model.Account = API.Account.getFromServer()
}