After writing my finest practices article about VIPER, I’ve made just a few adjustments 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 adjustments…

VIPER protocols

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

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

This fashion for instance my router objects are implementing the Router protocol, so if I make an extension on it, each single one could have that specific performance. It is a fairly small, however very nice addition that makes my modules far more highly effective than they have been earlier than. Truthfully talking I ought to have had this from the very starting, however anyway any further 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. You’ll find it on GitHub, it is a actually fundamental one, be at liberty to make use of it, you simply need to import VIPER in your challenge.

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. UIAlertController is the one I am speaking about. Really Robi (my true steel pal) recommended a surprisingly good normal resolution for the issue. His concept 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 beloved this method, so we have constructed it. Turned out, it is freakin superior. So we launched a brand new protocol for the module router, applied 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 plenty of different (related) issues as effectively. The fundamental implementation seems to be 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 {

    
}

After all this method can work for different VIPER elements as effectively, it is fairly straightforward to implment and the protocol oriented method provides 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 movement. In my final article I advised 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("Whats up from module A!")
    }
}

This fashion you’ll be able to skip your complete router layer, plus all of the enterprise associated logic can be applied within the presenter layer, which ought to be the one solution 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 further 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 internet 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 fashion 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

It is a WIP (work-in-progress) concept that I would wish to check out, however the fundamental idea is considerably like that I need to separate enter and output protocols for VIPER module layers. Additionally this IO differentiation will 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 will be manner too many objects within the Service/Objects listing, so because of this these could possibly 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, e.g. PresenterInput, PresenterOutput. We’ll see, however at first sight, it is looks as if fairly an over-engineered factor (hahaha, says the VIPER advocate 😂).

VIPER vs [put your architecture name here]

No! Please do not suppose that x is healthier than y. Architectures and design patterns are easy instruments that may be utilized to make your life simpler. In case you don’t love x, it is best to strive 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 12 months or two I will go loopy in love with reactive programming. Does it actually issues? I do not suppose so. I’ve discovered and tried so many issues through the previous, that I am unable to even bear in mind. 🧠

I am additionally consistently attempting to determine new issues, as you’ll be able to see this complete collection of articles about VIPER is the results of my studying progress & experiences. In case you actually need to grasp one thing, it is best to apply, analysis and take a look at loads, and most significantly be pleased with your successes and keep humble on the identical time. 🙏

That is it concerning the VIPER structure for some time. I hope you loved studying the entire collection. When you’ve got any questions, be at liberty to ask me by Twitter. 💭