Mastering the VIPER structure – The.Swift.Dev.

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 difficulty was that I needed 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 may 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 longer it is gona be like this. 😬

This transfer implied to arrange my VIPER protocols right into a customized framework, so I made one, with these elements. You will discover it on github, it is a actually primary one, be at liberty to make use of it, you simply need to 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 recognize UIAlertController is the one I am speaking about. Truly Robi (my true steel pal) recommended a surprisingly good basic answer for the issue. His thought appeared like this:

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

I liked this method, 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 at the moment are able to presenting error messages.

Observe that you should utilize the identical sample for many different (related) issues as nicely. The fundamental implementation appears like this one under, I hope you get the thought. 💡

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 {

    
}

In fact this system can work for different VIPER elements as nicely, it is fairly simple to implment and the protocol oriented method provides us an enormous win. 🏆

Presenter to presenter interactions

I additionally modified my thoughts in regards to the place of the delegate implementations taking part within the module communication move. In my final article I instructed you that I am storing the delegate on the router, however in a while I spotted that delegation is generally 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() {
        self.delegate?.didDoSomething()
        self.router?.dismiss()
    }
}



class BModulePresenter: Presenter, AModulePresenterDelegate {

    func didDoSomething() {
        print("Hey from module A!")
    }
}

This manner you possibly can 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 method to go. 🤪

Entities are right here to remain

Aside from the service layer generally 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 true VIPER entities.

IO protocols

This can be a WIP (work-in-progress) concept that I would wish to check out, however the primary idea is considerably like that I wish to separate enter and output protocols for VIPER module layers. Additionally this IO differentiation could 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 could be approach too many objects within the Service/Objects listing, so because of this these might be additionally grouped by modules (aka. entities).

Anyway, I am pondering of one thing like RequestEntity, ResponseEntity for service communication, and for the VIPER layer communication I might 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. In the event you don’t love x, it is best to attempt y, however you shouldn’t blame x, simply because that is your private opinion.

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

I am additionally consistently making an attempt to determine new issues, as you possibly can see this entire collection of articles about VIPER is the results of my studying progress & experiences. In the event you actually wish to grasp one thing, it is best to apply, analysis and take a look at lots, and most significantly be pleased with your successes and keep humble on the identical time. 🙏

That is it in regards to the VIPER structure for some time. I hope you loved studying the entire collection. When you have any questions, be at liberty to ask me via twitter. 💭