In iOS Mobile App Development Services, there is always a need to achieve a balance between writing clean and maintainable code and writing scalable solutions for large applications. That’s why traditional design patterns like MVC or MVVM do not suffice here, resulting in issues like overloaded View Controllers or ambiguous division of responsibilities. To overcome these problems, developers use the VIPER architecture to structure the code.
VIPER Architecture Implementation is a design pattern that helps to separate jobs, making it easier to work with, test, and scale applications. This blog describes how VIPER works, how it differs from other architectures, and how it affects iOS app development.
Principles of the VIPER Architecture
VIPER, an acronym for View, Interactor, Presenter, Entity, and Router is derived from the Clean Architecture. In VIPER, every layer is given a particular task to perform so that no layer is overloaded with responsibilities and functionality.
Thus, by setting strict boundaries between these components, VIPER Architecture Implementation ensures maintainable and scalable solutions, ideal for iOS App Development Services. This also supports the testing of each layer independently because all of them can be tested separately.
VIPER Components Explained
Every part of the VIPER architecture has its responsibility to make sure that business logic, presentation, and navigation are distinct. Here is the breakdown of each of the VIPER components and what each of them does in the architecture.
View
The View in VIPER Architecture Implementation is for displaying the interface and invoking user actions, which is critical for Custom iOS App Development Services. It does not do any business logic or any type of calculations but it does accept input and returns output. It simply relays user actions to the Presenter and redraws its interface according to the Presenter’s specifications.
Example:
In a weather app, the View probably includes the current temperature and conditions. If a user selects a new city to view, the View informs the Presenter about this action and the latter takes further actions.
This means that by decoupling the View from the business logic, the VIPER makes the interface simple, which makes it easier to maintain and change the user interface.
Interactor
The Interactor is responsible for all the business logic of the application. It is also charged with effecting queries whether local or network and processing the results before passing them to the Presenter. It does not interact with the View directly, keeping the business of managing data separate from displaying it—a best practice in Modular iOS App Design.
Example:
In the case of, for example, the weather app, the Interactor might get weather data from an API, change temperature scales, or work with the forecasts, and then send the data to the Presenter.
This is achieved by the Interactor to avoid combining the business logic with the UI controls and therefore the code is easy to maintain and test.
Presenter
The Presenter acts as the middleman between the View and the Interactor, supporting Clean Architecture in iOS Development. From the View, it gets user actions and, in return, sends requests to the Interactor to get or modify data. The Presenter then prepares the data to be displayed in the View but never changes the UI elements itself.
Example:
In the weather app, when a user enters a city to retrieve the weather information, the Presenter guides the Interactor to retrieve the data. After the presenter processes the data, it formats the data and sends it back to the View for presentation.
The Presenter’s responsibility of isolating the View and the Interactor is important for keeping the application de-coupled and testable.
Entity
The Entity layer comprises the data models that help in the determination of how data in the application should look like. These models are what is returned from the database or API and are often just plain data objects.
Example:
In the weather app, an Entity might define the Weather Data object which has parameters like temperature, humidity, and weather conditions.
Entities are important for data storage, encapsulating models and their schemata from the functions of the business process and the interface.
Router
It is the Router’s job to determine how to move from one screen to another in the application. When a user wants to navigate for instance from one screen to another, it is the Router that responds to this request. Now, it controls the flow of the application, naming the logic used to swap from one screen to another.
Example:
In the weather app, the Router can manage the navigation when a user clicks on the detailed weather forecast for the week. The Router would then trigger the change to a new screen with that information.
In the Router approach, the state transition is divided from other concerns, which makes the responsibility of handling transitions clean and distinct.
A Comparison of VIPER with Other Architecting Frameworks
It must be noted that VIPER is not the only architecture being used in developing iOS applications and it’s worthy to know how it differs from the traditional architectures such as MVC and MVVM.
VIPER vs MVC
MVC (Model-View-Controller) has been the most popular design pattern for many iOS applications. However, VIPER Architecture Implementation solves MVC’s main weakness, the Massive View Controller problem, by ensuring clear separation in iOS App Design Patterns.
VIPER solves this issue by clearly separating these responsibilities:
- The View is only responsible for presenting data.
- The Interactor is also responsible for the business logic.
- Navigation is at the discretion of the Router.
This leads to much cleaner and better testability because the View Controller is not overloaded with the logic.
VIPER vs MVVM
MVVM (Model-View-View Model) is another of the most famous architectures. Although it is an enhancement of the MVC pattern by adding a View Model to manage the UI, it still has the problem of combining business and presentation logic. VIPER, on the other hand, divides them more clearly, which gives a better implementation of single responsibility principles.
Why Choose VIPER for iOS Development?
VIPER provides several distinct benefits over conventional architectures, especially for large, intricate applications. Below are some reasons why developers choose VIPER:
Modular Design
As the VIPER module wraps up only one feature or screen of the application, the developer can easily manage and update features without any hindrance to the app. This modularity also facilitates ease of integration, since different teams can be working on different modules at a go.
Better Testability
One advantage of the decomposition of concerns in VIPER Architecture Implementation is that it supports iOS Application Testing Services with ease. As each component (View, Interactor, Presenter, etc.) has only one responsibility, testing is easier. Both mocks and stubs can be generated for individual components, which will help develop additional testing for the app.
Scalability
With applications growing, VIPER Architecture Implementation ensures no single component is overwhelmed, a crucial benefit for Scalable iOS Application Solutions. This characteristic makes VIPER well-suited to long-term, large-scale projects that will require sustained updating and maintenance.
Practical Example: Applying VIPER on a Login Screen
Let’s explore how VIPER Architecture Implementation is applied in a practical context, such as in Custom iOS App Development Services for a login screen.
- User Input: The user types a username and password in the View.
- Presenter: The Presenter takes this input from the View and passes it to the Interactor.
- Interactor: The Interactor then checks the login credentials by comparing them with a database or an API.
- Entity: The Entity saves the user’s credentials or the authentication tokens if required.
- Presenter: The Presenter decides if the login process has been completed successfully and makes an appropriate request to the View to notify the user about the unsuccessful login attempt or to move to the home page.
- Router: If login is successful, the Router goes to the next page (e.g., home page).
Potential Challenges of Implementing VIPER
While VIPER is powerful, it’s not without its challenges. Implementing VIPER can be overwhelming for smaller projects or teams unfamiliar with the architecture. The complexity of maintaining several layers per feature can also feel like over-engineering in simple applications.
However, once a team is comfortable with VIPER Architecture Implementation, the benefits far outweigh the challenges, especially for iOS App Development Services that require long-term scalability.
Conclusion
VIPER Architecture Implementation is among the cleanest, most scalable, and testable architectures, making it ideal for Custom iOS App Development Services. Due to the clear separation of tasks in five layers: View, Interactor, Presenter, Entity, Router, VIPER offers clear separation in applications, for scale and small. Although there is a relatively high initial cost, VIPER’s capacity for separation of concerns, testability, and collaboration makes it the best choice for long-term iOS development.