After writing my finest practices article about VIPER, I’ve made a number of modifications 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 modifications…
VIPER protocols
My generic challenge was that I wished to have a frequent interface for each single module element. 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 can 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. Actually 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 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 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. You understand UIAlertController is the one I am speaking about. Truly Robi (my true steel good friend) recommended a surprisingly good common resolution 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 are actually able to presenting error messages.
Notice that you should utilize the identical sample for many different (related) issues as properly. The essential implementation seems to be like this one beneath, 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 {
}In fact this method can work for different VIPER parts as properly, 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 collaborating within the module communication movement. In my final article I informed you that I am storing the delegate on the router, however in a while 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() {
self.delegate?.didDoSomething()
self.router?.dismiss()
}
}
class BModulePresenter: Presenter, AModulePresenterDelegate {
func didDoSomething() {
print("Hi there from module A!")
}
}This manner you possibly can skip your complete router layer, plus all of the enterprise associated logic shall 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 fundamental idea is considerably like that I need to separate enter and output protocols for VIPER module layers. Additionally this IO differentiation may 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 may be approach too many objects within the Service/Objects listing, so which means that these may very well 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, 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 best than y. Architectures and design patterns are easy instruments that may be utilized to make your life simpler. If you happen to 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 suppose so. I’ve discovered and tried so many issues in the course of the previous, that I am unable to even bear in mind. 🧠
I am additionally continuously attempting to determine new issues, as you possibly can see this entire collection of articles about VIPER is the results of my studying progress & experiences. If you happen to actually need to grasp one thing, it is best to apply, analysis and check out rather a lot, and most significantly be happy 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 at liberty to ask me by Twitter. 💭
