The very process of app development without following any dedicated app architecture is like following a path without any definite aim. Without any architectural design pattern, developers can’t lay a solid foundation for an app. The same principle follows in using iOS architecture as well.
In case any developer tends to ignore any of the iOS architectural patterns, it leads to:
- Clustered and cluttered code
- Unorganized modules
- Unscripted documentation
Here, the selection of optimal architecture is crucial because it pays off over time. This selection establishes a shared understanding between you and your developers. Ultimately, it saves your time and capital.
Let’s define some attributes of a good iOS modular architecture:
- Equal distribution of responsibilities among different entities
- Easy testability at every phase
- Low maintenance cost and ease of use
Now, it comes to choosing the right architecture for your next iOS app development project. Before choosing, keep one thing in mind there is no single iOS architecture and it depends on the project’s requirement.
Also Read: App Development Frameworks
This write-up will encircle the 5 most prominent iOS architecture design patterns.
Choose wisely and provide a solid foundation for your application:
- Model-View-Controller (MVC)
- Model-View-ViewModel (MVVM)
It is considered as one of the most popular iOS architecture in-app architecture designs. It is easy to use and highly recommended by Apple itself. iOS, MacOS, and watchOS use this as a default architecture. Its design patterns separate the presentation layer from the business logic.
It is equally popular in both web and app development, and it is a good fit for software design patterns for app and web development. It is more clear through the iOS app architecture diagram.
The Model View Controller architectural pattern differentiates concerns into 3 classifications:
- Model: It manages stores and data
It represents databases and can be illustrated the concept by using local storage on a browser.
- View: Graphical User Interface
It represents data in a form of chart, diagram, or table. It has all the desired functionality to interact with the user through click buttons.
Known as the brain of the application. It establishes a connection between the model and the view. To retrieve the data, it converts all the inputs from the view to demands in the model. It works like this:
- Receives input from view and translates the input through logic
- The model receives all the data
- The received data passes from the model back to view for the display
Attributes of MVC
- A much popular architecture in web applications
- It comes with good compatibility with web application architecture and divides responsibilities between the client and server
- Good for planning development
- Keep unnecessary dependencies at bay
- Extendable code and code reusing
- Can be maintained and modified easily
- Seamless Rails on Ruby support
- Model, View, Controller, each part can be tested independently
The Model View ViewModel is also a design pattern known for developing user interfaces. It is based on the pattern “Model View Controller” (MVC) and the applications based on MVVM patterns use multiple capabilities available on WPF, Silverlight Desktop/web, and Windows.
The Model View ViewModel (MVVM) pattern is a design pattern most commonly used for creating user interfaces. It is derived from the popular “Model View Controller” (MVC) pattern. Microsoft expression products are also based on MVVM
Here are the MVVM Principles:
The Simplicity Principle: Each view has a single ViewModel and ViewModel is only responsible to service a single View.
The Blendability Principle: Expression blend support
The Designability Principle: The ViewModel should supply Design Time Data
The Testability Principle: The ViewModel and Models should be testable.
Attributes of MVVM
- Known for its maintainability and keep remain agile to release successive versions quickly
- Comes with high extensibility and the ability to tweak the code (replace and add)
- Easy testing ability paves the way to write unit tests against a core logic
- Comes with a transparent interface to the view controller. It interacts with the view layer with the model layer for transparent communication.
The model-view-controller-ViewState architecture aims to build on MVC. It is somehow similar to MVVM when it comes to patterns. However, the view controller still determines the changes in the model; different from the view model in MVVM. To make this more efficient and manageable, it separates our view state and makes it more manageable.
In this case, the view state and model both are listened to by view controller. Reactive programming sets this observation.View controller does more notification work here.
MVCVS Model Updates
In case of any change, the updation of the document and view state is on view controller. All the possible changes to the view hierarchy happen through either the view state or the document model.
MVCVS View Changes
The view state and document view model are observed by the view controller and changes are done through these observations.
MVCVS View State
The view state is explicitly separate from the view controller. The view state is updated by the controller and listens to changes from it.
Test is done by integration tests for the architecture. It is better than MVC in the aspect that one tests logic to the document model and view model in a separate manner.
Read our blog on: iOS App Development Advantages
It is considered an adaptation of Clean Architecture of iOS applications. It consists of: View, Interactor, Presenter, Entity, and Routing. It is specially customized to build components around different user cases.
Generally, it requires different components, which makes it a difficult pattern to start with. Developers who rely on VIPER tend to use code generators as the amount of repeated code is required here.
The view displays what the presenter tells it to. Based on user interaction, it responds to the presenter with messages.
The interactor contains business logic on a per-use-case basis.
The view logic and view state come under the presenter. The view is changed as per the interator’s message
These are the basic models that the interactor uses.
The router controls which view will be displayed and what the next view will be.
Attributes of using VIPER framework
- It simplifies multiple complex projects
- A good fit to operable architecture for large teams
- Disassociates code for the purpose of easy testability and reusing of code
- Creates clear and well-defined interface
- It reduces the number of merge conflicts
- Makes the codebase look similar
ModelAdapter-ViewBlinder is an innovation in experimental design pattern. It removes the entire dependency on the controller and replaces it with view binders and model adapters.
View binders are a kind of wrapper class around the view class which provides bindings for changing the view based on user interaction on new information. They are immutable in nature and make iOS architecture patterns declarative.
Modal adapters and view binders are created before any view is made. Views are then created and bound to their respective view binders.
MAVB Model Updates
The view binder is notified once the view initiates action. The model adapter will reduce this message and make suitable changes in the model.
MAVB View Changes
The model adapter sends a message to the view binder once the model changes. Changes occur to view as per view binder handling.
MAVB View State
View state is stored in the model. View state data flows the same way as changes to the model
Code testing by the view binders happens in this iOS mobile application architecture. Here, view binders are verified for their behavior during user interaction when there is an update to the model.
A Road to Conclusion
If you have a look at the above-mentioned design patterns and consider them used them as popular iOS architectural patterns, you will certainly notice one thing. All the design patterns aim to make the UI more interactive for the app.
Well, each advanced iOS app architectural pattern has its own advantages and disadvantages, so choosing wisely as per the project requirement is quintessential. All the design patterns MVC, MVP, MVVM, MVCVS, and Viper are best-in-class and are customized to deliver the purpose they were used for.