Mastering the VIPER structure – The.Swift.Dev.

Discover ways to grasp the VIPER architectural design sample, with some protocol oriented programming methods utilizing Swift.


After writing my finest practices article about VIPER, I’ve made just a few modifications to the codebase. I used to be taking part in with these concepts in my thoughts already, however by no means had sufficient time to implement them correctly. Let’s me present you the modifications…

VIPER protocols

My generic situation was that I wished to have a widespread interface for each single module part. That is why I created easy protocols for the next:

  • View
  • Interactor
  • Presenter
  • Entity
  • Router
  • Module

This manner for instance my router objects are implementing the Router protocol, so if I make an extension on it, each single one could have that individual performance. It is a fairly small, however very nice addition that makes my modules far more highly effective than they have been earlier than. Actually talking I ought to have had this from the very starting, however anyway any more it is gona be like this. 😬

This transfer implied to prepare my VIPER protocols right into a customized framework, so I made one, with these elements. Yow will discover it on github, it is a actually primary one, be happy to make use of it, you simply must import VIPER in your undertaking.

Module protocols

Since I used to be utilizing VIPER it had this nice urge to implement a customized module for presenting system default alert messages on iOS. You realize UIAlertController is the one I am speaking about. Truly Robi (my true metallic good friend) prompt a surprisingly good normal resolution for the issue. His thought seemed like this:

Why do not we create a protocol for the router, so we may implement this on each different router, additionally we may merely name present(alert:) on them?

I cherished this strategy, so we have constructed it. Turned out, it is freakin superior. So we launched a brand new protocol for the module router, carried out a default protocol extension and voilà routers are actually able to presenting error messages.

Notice that you need to use the identical sample for many different (comparable) issues as nicely. The essential implementation appears like this one under, I hope you get the concept. 💡

import VIPER

class AlertModule: Module {

protocol AlertModuleRouter: class {

    func present(alert: AlertEntity)

extension AlertModuleRouter the place Self: Router {

    func present(alert: AlertEntity) {

protocol MyModuleRouter: Router, AlertModuleRouter {


After all this method can work for different VIPER elements as nicely, it is fairly straightforward to implment and the protocol oriented strategy offers us an enormous win. 🏆

Presenter to presenter interactions

I additionally modified my thoughts concerning the place of the delegate implementations taking part within the module communication move. In my final article I advised you that I am storing the delegate on the router, however afterward I spotted that delegation is usually associated to enterprise logic, so I merely moved them to the presenter layer. Sorry about this. 🤷‍♂️

import VIPER

protocol AModulePresenterDelegate {
    func didDoSomething()

class AModule: Module {

    func construct(with delegate: AModulePresenterDelegate? = nil) -> UIViewController {

        presenter.delegate = delegate


        return view

class AModulePresenter: Presenter {

    func someAction() {

class BModulePresenter: Presenter, AModulePresenterDelegate {

    func didDoSomething() {
        print("Good day from module A!")

This manner you may skip the whole router layer, plus all of the enterprise associated logic will probably be carried out within the presenter layer, which ought to be the one strategy to go. 🤪

Entities are right here to remain

Other than the service layer typically it is fairly helpful to have an entity wrapper with some extra metadata for the mannequin objects. That is why I additionally made an Entity protocol, and began to make use of it in my modules. For instance an online view module that may open a hyperlink can have a WebViewEntity with a title and a content material url property. 😅

import VIPER

struct AlertEntity: Entity {
    let title: String
    let message: String

The pattern alert module from above can use an AlertEntity with some properties that may outline the title, message or the buttons. This manner you do not actually have to consider the place to place these objects, as a result of these are the actual VIPER entities.

IO protocols

It is a WIP (work-in-progress) concept that I would wish to check out, however the primary idea is considerably like that I need to separate enter and output protocols for VIPER module layers. Additionally this IO differentiation might be mirrored on the service layers too (possibly the entire object “mess” from the service layer goes for use as IO entities sooner or later), by mess I imply that there might be manner too many objects within the Service/Objects listing, so which means that these might be additionally grouped by modules (aka. entities).

Anyway, I am considering of one thing like RequestEntity, ResponseEntity for service communication, and for the VIPER layer communication I may think about two separate protocols, eg. PresenterInput, PresenterOutput. We’ll see, however at first sight, it is looks as if fairly an overengineered factor (hahaha, says the VIPER advocate 😂).

VIPER vs [put your architecture name here]

No! Please do not assume that x is healthier than y. Architectures and design patterns are easy instruments that may be utilized to make your life simpler. For those who do not like x, you need to attempt y, however you shouldn’t blame x, simply because that is your private opinion.

My present favourite structure is VIPER, so what? Possibly in a yr or two I will go loopy in love with reactive programming. Does it actually issues? I do not assume so. I’ve realized and tried so many issues throughout the previous, that I am unable to even keep in mind. 🧠

I am additionally consistently making an attempt to determine new issues, as you may see this complete sequence of articles about VIPER is the results of my studying progress & experiences. For those who actually need to grasp one thing, you need to observe, analysis and check out so much, and most significantly be happy with your successes and keep humble on the similar time. 🙏

That is it concerning the VIPER structure for some time. I hope you loved studying the entire sequence. When you have any questions, be happy to ask me by twitter. 💭