Girish Kant Sood

Aug 07, 2019

Design patterns are pivotal tools for developers which helps them to maintain their engineering practices while also putting them to good use in app development. Together with various other patterns, these allow the developers to create robust & well functioning apps that use different style patterns & are not complex in managing. When the developers started to create user interfaces (UI), many attractive design patterns were used to simplify this process. In this article, I will compare the design patterns “Model View ViewModel (MVVM)”, the design pattern which has been gaining a lot of attention with “Model View Controller (MVC)”, which is favored by most iOS developers.

Model-View-Controller (MVC)

MVC can be defined as a structural software pattern made for implementing UI & also to separate an app into three main parts: the model, the view, & the controller. This pattern is widely used in web app development with programming languages such as Java, C, C++, etc. This pattern has been declared by many developers as valuable for reusing the object code & a pattern which enables to necessarily cut down the time of UI development in an app.

Its general purpose is to separate the functionality of backend & frontend which depicts the program. Some frameworks that use MVC concepts are PHP Codeigniter that have folders in their file structure called models, views & controllers. Sometimes frameworks put one aspect of the app in the controller & another one in the model. Model–view–controller is a software architectural design to put into action user interfaces on computers. The MVC split allows easy management of the complicated apps as one can focus on one facet at a time. It consists of three components that are:

1. Model - it is responsible for getting & manipulating data, in other words, it is the brain of the app. It interacts with databases such as MySql non-relational databases such as MongoDB. The model communicates with the controller & controller request for data through the model.

2. View - it provides the actual view of the app. The users see the UI of the app, it consists of CSS, HTML along with dynamic values from the controller. The user is allowed to modify the data.

3. Controller - it takes input from a user visiting the page. It primarily acts as a mediator between view & model & asks the model to get the data from the database so that the controller can load a view & then pass the data into it. Also, the controller can load the view without passing the data. They are also in charge of the flow control of app execution.

By this pattern, the elements have an outlined relationship with their interactions.

Model-View-ViewModel (MVVM)

MVVM, also known as model-view-binder is a software design pattern that clearly defines the architecture of an application i.e the three layers namely View, ViewModel, Model & how the layers interact with each other. We can reuse & maintain our code in a better way for WPF application, windows application & mobile application through MVVM. The main goal of MVVM as a pattern is to separate the view from ViewModel & model. It allows us to share the entire model throughout on these platforms. But view requires a platform-specific code so that the same UI design is not followed on every platform. It was created by Microsoft architects Ken Cooper & John Gossman. It was created particularly to ease the event compelled programming of UI. MVVM is divided into:

1. View - it is the user interface that the end user interacts with. It consists of every single element displayed on the screen such as texts, animation which excludes any code.

2. ViewModel - is located between the View & Model layers. This is where all the logic of the app is i.e what logic will be used to get expected results. It connects the UI elements in View to the controls in ViewModel through data binding. It can be understood as a way to view communicates with view-model through data binding.

3. Model - it is the abstraction of the data, in other words, it houses all the data required for an application to work, which is retrieved by the ViewModel upon its own receipt of input from the user through View. The communication between ViewModel & model is through notifications, which runs from model to view & vice-versa so that both view & model have the same value.

Why we should use MVVM over MVC

MVC pattern powers majority of iOS cocoa apps, which is easy to grasp & has little upkeep, but those who have used MVC know that it is not even close let alone perfect. The MVVM pattern provides an appealing choice. It is must to discern that MVVM is an extension of MVC & its advantages are deep & intelligent. Let us take a look at some of the advantages MVVM has over MVC:

1. Enhanced Testing - it is particularly hard to test view controllers due to their connection with the view. But testing can be made easier by transferring data manipulation to view model because view models can be easily tested due to the fact that they don’t have a reference to the object they are owned by. Unit test cases are also easy to write for view models.

2. Genuine Approach - its main advantage is that the view controller is a calculated component of the view layer. MVVM helps us to create a lot of elements than MVC which are reusable, smaller & can be tested. All this becomes a part of a genuine approach.

3. 2-Way Communication - MVVM pattern provides 2-way communication between its elements while MVC is prepared to provide a single way of communication exclusively. It aids a developer to design information closer to the readable elements.

4. The major difference between the MVVM & MVC pattern is that, in MVVM, the input starts with the view & not with the ViewModel. Hence, for as long as the view has a reference to ViewModel, ViewModel knows nothing about the view, allowing for 1 to many connections between other views & single ViewModel. But it is still better to have a 1 to 1 connection so that the ViewModel doesn’t have too much burden.

5. Security - MVVM also provides high security & better performance for non-complex applications than MVC.

6. Communication is Crystal Clear - The view model supplies a clear cut interface to view controller which it uses to populate the view layer & act with the model layer which in turn provides a clear cut contact between the four layers of the app. As the burden of the view controller is limited to manage the interplay between model & view layer, it bonds both the layers.


For me, MVVM has some really useful & everlasting smart uses to apply to different demonstration logic as compared to other logics as it is generally safe & sound design. The major goal is to separate the view, the model along with the logic that controls every single pattern to create a flawless project.

Hence, it is rewarding to use MVVM in such circumstances whenever data binding is achievable. As the resultant IView interfaces for every view are removed which provides for a smaller code to keep up for. Albeit, Swift has also increased the acceptance of the MVVM pattern. We use MVVM in every new project & it has simply transformed the way we consider & create the code. So if you haven't used MVVM till now, then we firmly back you to do so.

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