Mastering the VIPER structure – The.Swift.Dev.

After writing my greatest practices article about VIPER, I’ve made a number of adjustments to the codebase. I used to be enjoying 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 situation was that I needed 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 exact 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 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 parts. Yow will discover it on github, it is a actually fundamental one, be happy to make use of it, you simply must 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. You already know UIAlertController is the one I am speaking about. Really Robi (my true steel pal) steered a surprisingly good basic answer for the issue. His concept 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 strategy, 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 are actually able to presenting error messages.

Be aware that you should use the identical sample for plenty of different (comparable) issues as properly. The essential 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 {

    
}

After all this system can work for different VIPER parts as properly, 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 collaborating within the module communication circulate. In my final article I informed you that I am storing the delegate on the router, however afterward I noticed 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 fashion you may skip the complete router layer, plus all of the enterprise associated logic can be applied within the presenter layer, which ought to be the one method to go. 🤪

Entities are right here to remain

Other than 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 fashion 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

This can be a WIP (work-in-progress) concept that I might prefer to check out, however the fundamental idea is considerably like that I wish to separate enter and output protocols for VIPER module layers. Additionally this IO differentiation will be mirrored on the service layers too (perhaps 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 method too many objects within the Service/Objects listing, so which means that 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 might think about two separate protocols, eg. PresenterInput, PresenterOutput. We’ll see, however at first sight, it is looks like fairly an overengineered 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 less difficult. If you happen to do not like x, it’s 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 yr or two I am going to go loopy in love with reactive programming. Does it actually issues? I do not suppose so. I’ve discovered and tried so many issues throughout the previous, that I am unable to even keep in mind. 🧠

I am additionally continually attempting to determine new issues, as you may see this entire collection of articles about VIPER is the results of my studying progress & experiences. If you happen to actually wish to grasp one thing, it’s best to follow, 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 concerning the VIPER structure for some time. I hope you loved studying the entire collection. You probably have any questions, be happy to ask me by way of twitter. 💭