iOS Glossary: Architectural Patterns

The term "iPhone Operating System," which was the first build-up for the platform of mobile devices produced by Apple, including the iPhone, iPad, and iPod Touch, as well as the AppleTV, is the origin of the long-established abbreviation iOS.

From the notion of development, reliable alternatives for stability and enduring are offered by Apple, and this approximation is applied to their products, apps, tools, and frameworks. It is envisioned that every iOS device will be able to execute an app created by an iOS developer for the iPhone.

Improvising architectural patterns can sometimes be addictive, so beware: you may consider yourself asking more questions now than you did before reading this article, such as these:

Who is supposed to be in charge of a networking request: a Model or a Controller?

How do I insert a Model into a new View Model?

Who develops a new VIPER module: the Router or the Presenter?

Why care about choosing architectural patterns?

Predominantly, an architecture pattern is primarily characterized in terms of development as reusable solutions to trivial challenges in software design. These are the templates designed to assist in developing comprehensible and effective code. This method of patterning is reliant upon several constraints and limitations, encompassing complexities such as hardware performance, availability, utility status, and even specific business objectives.

While intriguing the architecture of an app, design patterns are an exact solution to a specific issue that might appear. Building scalable, reliable, reusable, and optimized software has indeed been associated with these qualities. In general, it assists in the software being standardized to such an extent that each component is distinct and supervises a single job, which greatly enhances the readability of the code.

Amidst main architectural design patterns, a few are acknowledged here:

•          MVC (Model–view–controller)

•          MVP (Model–view–presenter)

•          MVVM (Model–view–view-model)

•          VIPER (View-interactor-presenter-entity-routing)

Some architectural design patterns are presented in 3 categories:

Models —In iOS, the Model is a collection of different classes that represent the business logic and the rules by which the data can be altered and manipulated.

Views — View represents user interfaces through which users interact and view the app functionalities.

Controllers/ Presenters/ View-models — The Controller is a mediator between the model and the view. It is the actual manager which decides how a model should be represented in a view.

MVC: The Model-View-Controller architectural pattern, which is best suited for uncomplicated applications, is supported by iOS by default. Basically, it comprises a model, a controller, and a view. The user interface displayed to the user at a precise moment can be regarded as the view. The model is the data that is going to be presented in the view's components. Between them, the controller acts as a conduit. These three have constant companionship. A view is owned by a controller, and a model is associated with it.

The responsibility of the view is to make the user aware of its user interface. Finally, the view sends the controller the activities that were initiated by the user interface. The actions are often user-initiated or sometimes automatically generated. The primary duty of the Controller is to acquire these actions from the View and execute them. The model may be revised by the controller during its processing. This upgrading procedure can take some time. When the upgrade operation is terminated, the model notifies the controller, who then notifies the view to allow it to update its user interface with the updated data. View and Model communicate via Controller.

MVP: MVP is an evolution of Apple's MVC, where the view and presenter share responsibility for the view controller. While the presenter handles the actual business logic, the viewer retains control of the user interface. The unit test cases are all written over the Presenter, making unit testing smoother than it is with Apple's MVC because it uniformly distributes responsibility and makes testing the unit test cases less time-consuming. Yet, it slows down development as presenter implementation and layer binding require some more work.

MVVM:

An enhanced variation of the MVC design pattern is MVVM. With the addition of the view model, which now controls the way to integrate, MVVM unites the view and controller to establish a view.

The View Model initiates model modifications and updates itself intermittently to reflect them. Additionally, communication between View and the View model is simple because they are tightly connected. Due to the clearly stated separation of concerns, the decoupling produces thin, clean display controllers, which increase readability and maintainability.

MVVM is a technique for iOS mobile app development that aims to modularize code for UI architecture. It turns out to be the most important factor for developers.

VIPER:

VIPER is the leading and unequaled tool in trade for creating iOS app architecture patterns with a model based on modular data-source theory.

It is an architectural design pattern for iOS that resembles a spotless architecture approach. An application is divided into discrete and separate tiers of responsibilities using VIPER. View, Interactor, Presenter, Entity, and Routing is the letters that make up the acronym VIPER.

The View shows the input that the presenter has designated. Business logic is contained in the Interactor.

The Presenter takes in feedback from the audience and responds by requesting the Interactor for information. However, it also accepts data from the Interactor, processes the input using view logic, and instructs the view to show the data.

The smallest element in VIPER is called an Entity which is accountable for encapsulating data and contains the basic model objects.

The Router is in charge of managing screen switching. Additionally, it determines the navigation's true order.

A superior structure for iOS applications results from VIPER's architecture's adherence to the single repository principle. The outer layer is introduced, which quickly fixes the issue of switching between displays. VIPER lessens the probability of conflicts between the development team because roles are more precisely defined.

All in all, MVC as an architecture offers decent concern separation, but it frequently proposes the self-styled abstraction of "bloated view controllers," which is fixed by MVP and MVVM. They are hence effective architectural designs.

Conclusion

Apps that breach an architectural design pattern are tightly coupled, hard to substitute, and more vulnerable to bugs. Modern architectural styles apply to the creation of iOS applications. In the process of evolution, each pattern enhances the one before it. Clarified divisions between the components and their respective tasks promote the growth and support of the components. There is no panacea, so choosing an architectural pattern is a matter of weighing trade-offs in a particular situation. Therefore, it is natural to have a mix of architectures in the same app.

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