Top 82 Xamarin Interview Questions And Answers

Question 1

What is Xamarin?

Accepted Answer

**Xamarin** is a Cross Platform Mobile Development technology by Microsoft where we can develop the native app using the same code base across all platforms (iOS, Android, UWP) using the C# language. Xamarin uses two approaches for the app development:
* Xamarin.Forms and 
* Xamarin Native.

Xamarin.Forms uses MVVM & XAML while Xamarin Native uses native UI technology and MVC or MVVMCross Architecture.

Question 2

Explain _Lifecycle methods_ of Xamarin.Forms app

Accepted Answer

Lifecycle methods are set of methods which get executed when application enters into a specific state. Following are such methods:

*   `OnStart`: Executes when application starts from the beginning
*   `OnSleep`: Executes each time when application goes into the background
*   `OnResume`: Executes when application comes into the foreground from the Sleeping state

Question 3

What is the basic architecture of Xamarin.Forms project?

Accepted Answer

Xamarin.Forms can consists of four (this varies based on requirements) projects under one solution.

*   .NET Standard, PCL or Shared Project
*   iOS Project
*   Android Project
*   UWP Project

Here, .NET Standard, PCL or Shared Project contains all UI & Business logic inside it.

iOS, Android, UWP contains platform specific code containing Renderers or Dependency Services Implementations.

Question 4

What are the _various flavors_ of Xamarin Applications that can be made?

Accepted Answer

Xamarin allows two different ways of creating applications, based on the amount of code reusability and customization:

* The first approach is the **Traditional Native Approach** wherein platform-specific apps using Xamarin.iOSiOS and Xamarin.Android can be made. This way of creating apps is generally used when there is a lot of customization specific to the platform is required as it allows direct access to platform-specific APIs. Xamarin.iOS is used for iOS applications and Xamarin.Android is used to create Android applications.

* The second approach is creating apps through **Xamarin.Forms approach**. Xamarin.Forms are used when there is a possibility of reuse of a lot of platform-independent code and the focus is less on custom UI. The platform-independent code is separated and kept in Shared Project or PCL or .NET Standard Library and Platform Specific projects consume this common code by including it.

Question 5

How to display static HTML string in Xamarin.Forms?

Accepted Answer

We can use WebView control to display `static` HTML `string`. `WebView` can be used to display Websites, HTML string, Documents, Local Files depending on the platform support.

Question 6

What is the difference between `Margin` and `Padding` properties?

Accepted Answer

* `Margin` property represents the distance between the element and its adjacent elements and is used to control the element's rendering position, and the rendering position of its neighbors. Margin can be specified on `Layout` and `View` classes.

* `Padding` property represents the distance between an `Element` and the child elements of it and thus it is used to separate the control from its own content. `Padding` values can be specified on `Layout` classes.

Suppose, two adjacent elements have a margin of value 20 pixels assigned, what will be the distance between these two elements? Why?

The distance between two elements will be 40 pixels in this case, because, `Margin` property values are `Additive`. In addition to this, if `Margin` and `Padding` both are applied, then the distance between element and its content will be `Margin + Padding`.

Question 7

Name few widely used _Layout Controls_

Accepted Answer

*   `Frame`: It contains a single element as a child having a default padding of 20.
*   `Grid`: It is used when UI components are to be arranged into Rows & Columns.
*   `StackLayout`: It is used when UI components are to be arranged either horizontally or vertically.
*   `ScrollView`: It enables the scrolling for a child element if required. It has one child only.

There are other Layout Controls too like `AbsoluteLayout`, `RelativeLayout`, `ContentView`, `ContentPresenter`, etc.

Question 8

How to store simple `Key-Value` data?

Accepted Answer

Xamarin.Forms's `Application` class exposes the `Application.Current.Properties` `Dictionary` which is used to store the simple Key-Value pair data. The `Properties` dictionary uses a `string` key and stores an object value.

Question 9

What is Xamarin.Forms and what are the benefits of using it?

Accepted Answer

**Xamarin.Forms** is a Cross-Platform Toolkit which helps share Business Logic as well as UI using XAML across all supported platforms.

It uses MVVM pattern along with Binding into the XAML UI to accomplish this. It produces pure native controls for each individual platforms. Using Xamarin.Forms, we can share the whole business logic as well as UI among all supporting platforms like iOS, Android and UWP. It also provides a way for platform specific customization of any native controls using Renderers. Thus, we can almost share about 80-90% of code across platforms. We can say Xamarin is the King of Cross Platforms.

Question 10

What is is the difference between `ListView` & `TableView`?

Accepted Answer

The ListView and TableView controls are so similar, you can think of them as a single control. The major difference between the two is the manner in which they lay out their items, and it’s easy to change the layout so each control emulates the other.

* The ListView control displays its data stacked vertically, much like a standard listbox. Use this control to display an ordered list of data, especially long lists that require scrolling like a list of email messages, a list of contacts, or search results.

* The TableView control displays its data stacked horizontally in rows (although you can alter this behavior and have it displayed in columns first, as well). You use this control when you need more space for rich visualization of each item to be displayed.

One of the big differences is ListView provides you a ItemsSource and a Itemtemplate and TableView does not. So items must be added as children manually.

Top 82 Xamarin Interview Questions

What is Xamarin?

Explain Lifecycle methods of Xamarin.Forms app

What is Xamarin.Forms and what are the benefits of using it?

What is the difference between Margin and Padding properties?

What is the basic architecture of Xamarin.Forms project?

How to store simple Key-Value data?

How will you navigate from one page to another?

What are the various flavors of Xamarin Applications that can be made?

What is is the difference between ListView & TableView?

What are Pages in Xamarin.Forms?

What is the difference between Xamarin.Forms & Xamarin Native?

What is App.cs class?

Name few widely used Layout Controls

Which Languages are supported for Xamarin development?

How to display static HTML string in Xamarin.Forms?

How to perform Binding in Code Behind?

What is ResourceDictionary?

What is info.plist in Xamarin.iOS ?

What are Triggers? How many types of Triggers are available?

What is the special meaning with AndExpand Suffix with each LayoutOptions?

What is XAML Markup Extensions?

What is Behaviors? Give some examples where we should use Behaviors?

Explain .NET Standard Libraries For Sharing Code on Xamarin?

What is ViewCell and How many types of built-in Cells are available?

What are the advantages and disadvantages of using XAML in Xamarin.Forms?

Explain how to use shared projects in Xamarin?

What is View-to-View Binding?

What is the purpose of INotifyPropertyChanged?

What is Fresh MVVM?

What is the difference between XAML & AXML in Xamarin Technology?

What is Custom Renderers and what is its purpose?

How To Share Code Between Cross-Platform Applications on Xamarin?

What is the difference between Xamarin.Forms and Xamarin Native?

How many types of Pages are available in Xamarin.Forms?

What are Effects and when should they be used?

How many ways can we share the code?

How to do Xamarin.Android applications work?

What is difference between ControlTemplate & DataTemplate?

What is the difference between PCL & _Shared Project?

What is the purpose of XAML Compiler (XAMLC)?

What is TestFlight?

When would you use the NavigationPage as a MainPage?

What are Custom renderers in Xamarin.Forms?

What is Dependency Service and how it functions on Xamarin.Forms?

What is the purpose of InitializeComponent() method in Page?

How many ways we can Bind data?

What is Xamarin.Essentials?

Which best practices to follow while designing the XAML Page?

What is MessagingCenter?

Is there any benefit in binding a ViewModel in backend .cs file?

What the Xamarin platform consists of?

What are the disadvantages of Xamarin for Android development?

What is Effects and When should we use it over Custom Renderers?

What are Services in Xamarin.Android?

Name some types of Behaviors in Xamarin?

How to design separate layouts or functionality between Phone & Tablets?

What is the difference between Entry and Editor in Xamarin.Forms?

Why do we need to create a Custom ViewCell?

How to render different types of ViewCell in the same ListView during runtime?

How to call a specific method for some specific Platform only?

What are some features of Fresh MVVM?

How does compilation work for Xamarin?

What is DependencyService? Describe steps for the implementation.

What is MVVM Light?

How to make iOS native libraries accessible in Xamarin apps?

How many types of different XAML Markup Extensions do you know?

How do we provide Platform specific styling or values in XAML?

Name some types of keys defined in info.plist files

What is MVVM Cross?

How many ways you can Bind a ViewModel with XAML?

How to increase the ListView performance?

Explain what is linking process on Xamarin

Explain what happens when the Xamarin.Android application compiles?

Name some limitation of Xamarin.iOS

So, what is the difference between MessagingCenter and Events?

Why AOT is used for Xamarin.iOS?

What is Registrar in Xamarin.iOS?

Can we really declare Parametrized ViewModel instance as BindingContext in XAML?

What are Android Callable Wrappers (ACWs)?

What is the difference between `Margin` and `Padding` properties?

How to store simple `Key-Value` data?

What is is the difference between `ListView` & `TableView`?

What is `App.cs` class?

What is `ResourceDictionary`?

What is `info.plist` in Xamarin.iOS ?

What is the special meaning with `AndExpand` Suffix with each `LayoutOptions`?

What is `ViewCell` and How many types of built-in Cells are available?

What are the advantages and disadvantages of using `XAML` in Xamarin.Forms?

What is the purpose of `INotifyPropertyChanged`?

What is difference between `ControlTemplate` & `DataTemplate`?

When would you use the `NavigationPage` as a `MainPage`?

What is the purpose of `InitializeComponent()` method in Page?

What is `Xamarin.Essentials`?

Is there any benefit in binding a ViewModel in backend `.cs` file?

Why do we need to create a Custom `ViewCell`?

How to render different types of `ViewCell` in the same `ListView` during runtime?

What is `DependencyService`? Describe steps for the implementation.

Name some types of keys defined in `info.plist` files

How to increase the `ListView` performance?