Xamarin Interview Questions and Answers

Are you planning to make a career as a Xamarin App Developer but confused about what you need to do to answer those tricky interview questions in your Xamarin job interviews? Have no fear! Being aware of what interviewees face during the interview sessions, our team of experts and former interviewers have compiled a set of 30 Xamarin interview questions and answers that will help you crack your next Xamarin job interview, allowing you to answer all the questions with confidence and self-assurance.

1.What is Xamarin?

Ans:

Xamarin is a company that builds the software. The main operation of Xamarin is to build mobile apps that work on cross-platforms. It is used to build the UI for Android, iOS, and Windows operating system. Xamarin application shares the codebase. Xamarin’s feature is similar to the native application. A developer can download the Xamarin tools in Visual Studio.

2.What is the advantage of Xamarin Development?

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Benefits of Xamarin Development are:

• The user interface is simple and native.
• Developers can use Xamarin to make cross-platform apps.
• The chances of the bugs are less.
• We can create an app for iOS, Android, and Windows using the same codebase.
• Xamarin has powerful community support.

3.What are the disadvantages of Xamarin Development?

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Disadvantages of Xamarin app Development are:

• The development of user interfaces in Xamarin is Time-Consuming.
• The apps created in Xamarin have a large file size. These apps are mostly between the 3 MB to 15 MB in size in the store.
• Even apps share the code across the platform, but there is also a need for the developer to create the linkage in the OS, which is difficult for the user.

4.What are the development approaches in Xamarin?

Ans:

Xamarin has two approaches for app development. These are

• Xamarin.Forms: Forms are the choices for the developers who want to create one application for all the separate mobile platforms, which are Windows, iOS, and Android.
• Xamarin Native: This approach is used in those scenarios when we want to create a separate version of the same App for different platforms. Developers can use Xamarin.iOS, Xamarin.Android and Xamarin.Windows libraries to create the applications for each particular platform.

5.What are the differences between the Xamarin and Xamarin.Forms?

Ans:

The differences between the Xamarin and Xamarin.Forms are:

Xamarin	Xamarin.Forms
Xamarin is an app development tool to create cross-platform mobile applications.	Xamarin.Forms is a UI toolkit to develop the application.
Developers can use Xamarin.iOS, Xamarin.Android and Xamarin.Windows to create the application which is based on the particular platform for which the apps are created.	Developers can use Xamarin. Forms to create the one native version of the App which can run the entire mobile platform.

6.What is Xamarin Profiler?

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Xamarin Profiler is a tool which is used by the developers to keep an eye on the information about the particular App inside the Visual Studio. With the help of Xamarin Profiler, developers can easily analyze the App’s behavior. We can use the profiler to track the application’s memory information and can sample its statistics.

7.What is Xamarin Insights?

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Xamarin insight is a tool that allowed the developers to identify and track the issue with the apps in real-time. We can also use this for the monitoring system to report the problems. Xamarin introduced Xamarin Insight in October 2014. However, it was closed on March 31, 2016. In today’s time, developers can believe in Visual Studio App Center for the same functionality that is provided by the Xamarin Insights.

8.What is Xamarin.Forms?

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Xamarin.Forms is a framework which is used to build the user interface in the mobile application. In the same codebase, developers have to write the UI separately for each platform. This is time consuming and difficult process. Xamarin.Forms allows the developer to create just one UI which can be used across all platforms like Android, iOS, and Windows.

9.Which programming language supports the Xamarin?

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Xamarin supports three languages in the development of mobile applications:

• C#
• F#
• Visual Basic.NET

10.What is the role of XAML in Xamarin?

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XAML or Extensible Markup Language is a special tool that allows the developer to define the user interface in Xamarin app development. XAML has a vital role in Xamarin, but it is not necessary for app development in Xamarin.Forms. Xaml works with ModelView-ViewModel or MVVM architecture of an application.

11.What is Xamarin Studio?

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Xamarin Studio is a standalone IDE for developing the cross-platform mobile application, which is based on the open-source project Monodevelop.

12.What are the differences between the Xamarin Studio and Visual Studio?

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Both Xamarin Studio and Visual Studio are IDEs used to develop the Android, iOS, Class Library, Console, PCL, and Windows Phone application. Both Xamarin Studio and Visual Studio support F#.

Xamarin Studio	Visual Studio
Xamarin Studio works on both Windows OS X environments.	Visual Studio is available only for the windows environment.
On Windows, Xamarin Studio doesn’t support windows phone and iOS project.	In Visual Studio, we can create any app.
Xamarin Studio on Windows supports only Xamarin.Android project.	Visual Studio supports Xamarin.Android, Xamarin.iOS, and Xamarin.Windows project.

13.What is the lifecycle of Xamarin.Forms apps?

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Xamarin.Forms is a platform to develop the cross-platform mobile applications by using the XAML for Front-End and C# for the backend of the application. In Xamarin.Forms application, we can share all code. Xamarin.Forms also give the 100% API coverage of Android and iOS native APIs. So that, we can develop native Android, iOS, and Windows apps.

When we create Xamarin.Forms application we will see four projects:

• Portable Project: This is the project where we will write 95% of our application code, and this code is shared in all the three platforms.
• Android: This is the project where we set the Android application icon and splash screen, and all the other code will come from the portable project.
• iOS: In this project, we set the iOS application architecture and icon.
• Universal Windows: Universal Windows Platform is the application platform

14.What are the types of data binding modes in Xamarin?

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The different types of data binding modes are:

• Default
• One way: changes in the source affect the target
• Two way: Changes in the source and destination affect each other

15.What is the difference between the Xamarin and Mono?

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Xamarin	Mono
Xamarin is a powerful solution for building awesome apps.	Mono is used in those cases when we want to build an app for a single platform. In that case, there is a need for a Native platform.
With the help of Xamarin, we can create Native apps for multiple platforms via the same IDE, APIs, and Language.	Native mobile apps are built on Android, iOS.Java, and Windows.
Using Xamarin, we can skip the extra development time for each platform.	Using Mono, we cannot skip the extra development time for each platform.
Xamarin apps are accessible for more comprehensive ranges at a lower cost.	Mono apps are accessible for the broader ranges at a higher cost.

16.What are the different scenarios used in Xamarin.Forms?

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The following are the different types of scenarios that are used in Xamarin.Forms:

• View to View binding
• Backward binding
• Binding with the models
• Binding with the collections

17.What is data binding in Xamarin?

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Data Binding is a technique that is used to synchronize the source of the data with the user interface. When the data binding is done and the data or our business model changes, then it shows the changes automatically to the UI elements and vice versa.

18.What is the Xamarin test cloud?

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The Xamarin test cloud allows us to test the mobile application on various devices. The Test cloud is also used for automated testing in many real devices simultaneously.

19.How to set up the Xamarin?

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For Xamarin set up, there are four steps:

• Download the Xamarin Installer
• Run the installer
• Configure it
• Activation of Xamarin

20.What are the types of layout control in the Xamarin.Forms?

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Different types of layout control in Xamarin.Forms are:

• Stack Layout
• ContentView
• Frame
• ScrollView
• TemplateView
• Absolute Layout
• Grid
• Relative Layout

21.What are the different kinds of Pages present in the Xamarin.Forms?

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 The different types of pages present in the Xamarin.Forms are:

• Content page- This type of page displays a single view, often a container such as a stack layout or the scroll view.
• MasterDetail page- MasterDetailPage is a page that manages the information between the two related pages.
• Navigation Page- Navigation page manages the navigation of the pages.
• Tabbed Page- Tabbed Page helps the navigation of the children page using the tab.
• Template Page- The Template page helps to display the content of the full page with a control template.
• Carousal Page- This page allows the swipe gesture between the subpages, such as a gallery.

22.What are the advantages of Xamarin?

Ans:

Benefits of Xamarin are:

• We can deliver the native iOS, Android, and Windows app using the existing skills, and code (C#, XAML).
• We can take full advantage of Native APIs with Xamarin Technology.
• Xamarin Component Store allows us to add the high-quality components to our App directly from IDE, including controls, web service APIs, and more.
• PCL/shared project makes the development easy for developers to share the same code base across different projects.

23.What are the code-sharing techniques in Xamarin.Forms?

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There are two methods of sharing the code between the cross-platform applications:

• Portable Libraries (PCL)
• Shared Projects

The goal of the code-sharing strategy is to support the architecture where multiple platforms can utilize a single code base.

24.What is the difference between the portable class library and shared projects?

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Portable Class Library

• We create Class Library in .Net to reuse our code or to make our code reusable with the same type of application only, but that might not work for some conditions. Here we assume, we have created the class library for WPF or any other kind of application. And if we want to access the same type of class library for Windows 8 or Windows phone application, then in this scenario, we can’t refer this as a class library.
• We want the same application for all the platforms to make our life easy. We want the same application used on multiple platforms. Microsoft technology is growing day by day, and it covers every device. All types of applications we can build and validate within one framework on all types of platform Windows, Web, Mobile, or Tab.
• PCL solves this problem. .Net 4.5 introduced the Portable Class Library (PCL.for developing the business logic in one location, and we can use this library end to end in all types of applications or all platforms (Windows, web, or Mobile.on .Net Framework.
• The figure shows the flow of the Portable Class Library (PCL). All these applications run on the .Net Framework. All these applications have different environments and platforms, but they all can easily use the Portable Class Library. In other words, we can say that we only need to prepare the UI and do the DataBinding of our application for all the windows, web and mobile, because the same business logic can then use the entire platform.

Shared Project

A shared project is a project that contains standard code and linked to each specific platform library or App. It is compiled as a part of the platform-specific code. To develop a nice solution that is based on a shared project, there is a need to architect it to have the core features in the shared project. Here possibly, we may use partial classes, abstract classes, and interfaces to manage the objects which are specific for each platform in the platform-specific project. These kinds of projects are good when we are in a prototype phase because it is fast to implement the shareable project for the common code. We can use all the advantages of the platform-specific Framework.

Shared Code can be branched base on the platform using compiler directive (e.g. #if_Android_,#if_iOS_,#if_Windows_Phone_App.etc.)

• No output assembly
• Refactoring operations, not update automatically.

25.What are the advantages of XAML?

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The advantages of XAML are:

• XAML gives a clean division of the application and its code. Thus, it enables a clear developer-design flow.
• XAML is more crisp and precise than a similar code.
• XAML has the parent-child hierarchy of user-interface objects with greater visual interface simplicity

26.What are the Views?

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Views are known as control of widgets. They can be visual objects such as Label, Button, Entry, BoxView, ListView, TableView, etc. All the UI elements are the sub-classes of view.

27.What is the difference between ListView And TableView?

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ListView and TableView controls are similar. We can take them as a single control. The major difference between them is how they layout the items.

• ListView: ListView control displays the stacks of data vertically. It is just like a standard Listbox. We use this control to display the order of data in the list, especially the long list, that requires scrolling, like a list of email messages, a list of contacts, or search results.
• TableView: TableView displays the stacks of data horizontally in rows. We use this control when we need more space for rich visualization of the item to be displayed.

28.What are the types of the App which use Xamarin?

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The different types of apps which use the Xamarin are:

• OLO- an online platform to order food.
• The World Bank survey app- This App is used for the global survey.
• Storyo- This App helps to create videos from the picture.
• Freshdirect- This App is our friendly grocer.
• Just Giving- a philanthropic interface.

29.What are the different types of scenario used in Xamarin.Forms?

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The scenario used by the Xamarin.Forms are:

• View to view binding
• Backward bindings
• Binding with the collections
• Binding with the models

30.What are the apps designed by Xamarin for Android?

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The apps designed by Xamarin for Android are:

• The secret society
• Parental Access
• Toolwiz cleaner
• iLearnForKids
• Goal 2014 Football manager

31.Name the apps that were designed by Xamarin for iOS?

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 The apps that were designed by Xamarin for iOS are:

• QuickPLan- Project Plan HD
• NewsPager
• Apocalyspe Archer: Zombie invasion
• Stone Skimmer: Skimming action game

32.How Xamarin.Android applications work?

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Xamarin.Android applications depend on Microsoft’s Mono Virtual Machine. Mono is Microsoft’s open-source implementation of the .Net Framework, which is based on open source standards of C# and CLR. Mono was launched in the year 2001. It was created to allow the .Net applications to work on the Linux platform, but was later modified to support the development on various devices, including embedded systems.In Xamarin, Mono works in parallel with Android’s ART. On Android, most of the system facilities like Audio, Graphics, OpenGL, and Telephony are not available directly to the native applications. They can be added through the Android Runtime Java APIs, which is available in one of the Java.*namespaces or the Android.*namespaces. The native applications then interact with the exposed .NET APIs. These APIs then, through the Android Binding, call the Android runtime Java APIs.

33.What is Fresh MVVM?

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Fresh MVVM is a super light MVVM framework which is designed specifically for Xamarin.Forms only. Its design is easy, simple, and flexible. It is easy to learn and uses the convention over configuration.

Fresh MVVM is a little different from MVVM. FreshMvvm uses the concept of Page and PageModel instead of View and ViewModel.

34.What is the difference between the MVVM Cross and MVVM Light?

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MVVM Cross: MVVM Cross is a .NET cross-platform MVVM framework. It allows us to make a cross-platform solution for platforms such as Xamarin. Forms, Xamarin.Android, Xamarin.iOS, Xamarin.Mac and WPF. It is an inactive state of development.

MVVM Cross requires the application to be divided into two parts: Core and the UI.

The Core part contains the View Models, Service, Models, and the Business logic, whereas the UI part consists of the different views and platform-specific code that interact with the core. The views are the View Screens, which contain the graphical content. In addition to Core and UI, the application may contain additional libraries for various functionalities.

Features that are provided by MVVM Cross are:

• An MVVM architecture pattern
• A flexible Navigation system
• Data binding to allow automatic binding with the source to target.
• Platform-specific support
• Inversion of Control Container
• Dependency Injection engine

Consequences of MVVM Cross are:

• It has an excessive learning curve and lacks a Wiki for how to get started developing the apps.
• MVVM Light: MVVM Light is another Framework that allows the creation of Enterprise-Grade apps using the MVVM Architectural pattern on Xamarin. MVVM Light enables the developer to create and develop MVVM applications on a variety of platforms like Xamarin. Forms, Xamarin.Android, Xamarin.iOS, UWP, and WPF. It allows us to separate the View from Model and hence write the testable and extensible applications. It does not support async.

MVVM Light application is divided into the following parts:

• View: It is a platform-specific user interface which is associated with the screen.
• ViewModel: It exposes the data and related properties of the data.
• ViewModel Locator: It registers custom ViewModels.

35.What is the need of the Model-View-ViewModel (MVVM .pattern in Xamarin?

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The Model-View-ViewModel can be used on all platforms. It intends to provide a clean separation between the user interface controls and their logic.

• During the development process, developers and designers can work independently on their components. Designers can concentrate on the view, and if they are using Expression Blend, they can generate sample data. On the other hand, developers can work on the view model and model components.
• Developers create the unit tests for the view model and can create the model for the view.
• It is easy to redesign the UI of the application without touching the code because the view is implemented entirely in XAML. A new version of the view should work with the existing view model.
• If there is any existing representation of the model that binds the existing business logic, this can be difficult or risky to change. In this scenario, the view model acts as an adapter for the model classes and enable us to avoid making any major changes to the code of the model.

36.What is NuGet and how this can be useful in App development?

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NuGet is the most popular package manager for the development in .Net. It is present in Xamarin Studio 5 and Visual Studio. We can easily search and add package/third party libraries to the Xamarin.Forms using IDE.

37.What is the HTTP client?

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HTTPClient helps the developers to connect with the external world through the internet using the REST-based services. HTTPClient class is used for sending the HTTP requests and receiving HTTP response from a resource, which is identified by URI. HTTPClient class present in System.Net.HTTP namespace.

38.What is ResourceDictionary?

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ResourceDictionary is used to define the XAML Resources, which can be reused more than once throughout the Xamarin.Forms application.

• Xaml Resources are the definition of objects which can be used more than once.
• ResourceDictionary allows all the resource objects declared at one place.
• We can define Styles, ControlTemplates, DataTemplates, Colors, and Converters into the ResourceDictionary.

In XAML, resources can be accessed at the Element level (inside specific element), Page (inside page.level or Application Level (inside App.Xaml).

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

Ans:

Xamarin.Forms :

Xamarin.Forms are used when:

• the requirement of the code is less in the platform-specific scenario.
• Code-sharing is more important than custom UI.
• The UI is not complex.

Xamarin Native:

Xamarin Native is used when:

• a lot of platform-specific code is required.
• Custom UI is more important than code sharing.
• When platform-specific APIs are used.

40.What is the App.cs class?

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App.cs is the main class of the App which offers features like:

MainPage: It helps us to set the initial page of the App.

Properties Dictionary: It helps us to store the values across the state of the lifecycle.Static Current Property: It gives the instance of the current application object

41.What is the lifecycle method of the Xamarin.Forms App?

Ans:

Lifecycle methods are the set of techniques which are executed when the application enters into a specific state. The ways are:

• OnStart: This method will run when the application starts from the beginning.
• OnSleep: This method will execute when the application goes into the background.
• OnResume: This method will execute when the application comes in the foreground from the sleeping state.

42.What is the purpose of XAML compiler (XALC)?

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Using the XAML compiler, we can directly compile XAMLs into intermediate (IL.language.

Benefits:

• It performs the compile-time checking to find the error in XAML. At compile time it notifies the user about any mistake.
• It removes the overheads and initialization time for XAML elements.
• It doesn’t include the XAML file into the final assembly, and thus it reduces the assembly time.

43.What is XAML namespace declaration?

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XAML namespace is the declaration of the namespaces on top of the XAML file. There are two declarations available within the root element when we create any new XAML UI. Here is the default declaration of the xmlns without any prefix:

• xmlns=”http://xamarin.com/schemas/2014/forms”  

The second declaration uses the x prefix:

• xmlns:x=”http://schemas.microsoft.com/winfx/2009/xaml”  

All declaration of the namespace which uses the prefix is a non-default declaration.

Suppose we want to bind the ViewModel with XAML and that ViewModel is declared inside the namespace, “XamSample.ViewModels”.

• xmlns:vm=”clr-namespace:XamSample.ViewModels; assembly=XamSample.ViewModels”  

Then we can access the element from inside this namespace using VM prefix.

44.What is the way of navigation from one page to another?

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After clicking on the button of the first page, we call the following method through which we can navigate from one page to another page.We have to use the “Navigation” page property which is available under the ContentPage class. This code is written in the coding page of the MainPage.XAML file.

45.What is ViewCell?

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A ViewCell is a small individual element which represents a single item of the ListView or Table. A ViewCell is not a visual element, but it is a description of the template which creates the visual aspect.

46.What are the types of Built-in cells?

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The types of built-in cells are:

• TextCell: It is a cell that consists a Title/Primary text and a Detail/Secondary text label.
• ImageCell: It is a text cell which includes the image component in the left.
• SwitchCell: This cell contains Label and the toggle switch.
• EntryCell: This cell contains the Label and single line of textbox which can be used to enter the data.

47.What is the difference between ControlTemplate and DataTemplate?

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ControlTemplate: This template decides how the control should look. It defines the representation style for control.For example, A Button can contain Image and Text.

48.What are the triggers? How many types of triggers are available?

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Triggers allow us to declare actions in XAML, which changes the appearance of the control when specific condition met for a particular property of the control.

We can add triggers at control-level, page-level, or application-level in the resource dictionary. Here are the four types of triggers available. These are:

• Property Trigger: This trigger executes when the property of the control set a particular value.
• Data Trigger: This trigger is similar to a property trigger, but it uses the data binding.
• Event Trigger: This trigger occurs when an event occurs on the control.
• Multi Trigger: This trigger allows us to set the conditions of multiple triggers before the action occurs.

49.What is hockey app?

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Hockeyapp offers the testing service for iOS, Android, and Windows phone.

50.What is TestFlight?

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 Apple is the owner of the TestFlight. This is the primary way of the beta test of our Xamarin.iOS apps.

51.What are the types to create the Xamarin applications?

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Here are the three ways to build the apps in Xamarin.

• Xamarin.Forms  
• Xamarin.Android  
• Xamarin.iOS.

52.What is the difference between Native App and Cross Platform APP?

Ans:

• Native App: If we want to develop native apps, we need to choose the specific native language (C#, Objective-C, Swift, and Java.for developing specific native app for Windows, Android, iOS.
• Cross Platform App: This is the way to develop all three mobile apps using single code base wrapped in a native application layer, but it always requires customization of interfaces to native languages.

53.Xamarin history?

Ans:

• Xamarin is a Microsoft-owned San Francisco, California based software company founded in May 2011 by the engineers that created Mono, Mono for Android and MonoTouch .
• Novell had granted a perpetual license for Mono on july 2011 for MONO 
• On May 16, 2011: Miguel de Icaza announced on his blog that Mono would be developed and supported by Xamarin,
• December 2012, Xamarin released Xamarin.Mac which allows developers to build C#-based applications for the Apple OS X operating system and package them for publishing via the Apple App Store.
• Xamarin 2.0 was released in February 2013 Xamarin.Android and Xamarin.iOS that make it possible to do native Android, iOS and Windows development in C#, with either Visual Studio or Xamarin Studio.
• Xamarin.forms: Introduced in Xamarin 3 on May 28, 2014 and allows one to use portable controls subsets that are mapped to native controls of Android, iOS and Windows Phone.
• On February 24, 2016: Microsoft announced it signed a definitive agreement to acquire Xamarin
• On March 30, 2016: Microsoft acquired the xamarin. And made it for all with free of cost.

54.Mono vs. Monodevelop vs Xamarin

Ans:

• Mono: It is a framework and an open source implementation of Microsoft’s .NET Framework based on the open standards of European Computer Manufacturer’s Association (ECMA.for the C# language and the Common Language Runtime. And Mono allows C# developers to write cross platform code targeting Windows, Mac OS X, Linux, Android, and iOS. 
• MonoDevelop: It is an open source integrated development environment (IDE.for Linux, OS X, and Windows. Its primary focus is development of projects that use Mono and .NET frameworks.Xamarin: a subsidiary of Microsoft – is a company founded by the engineers who created Mono. Xamarin is the primary maintainer and commercial sponsor of Mono. It provides professional developer tools that make cross platform code easier to author, test, and maintain.

55.What are the programming languages that support Xamarin Development?

Ans:

• Xamarin is unique in this space by offering a single language – C#, class library, and runtime that works across all three mobile platforms of iOS, Android, and Windows Phone (Windows Phone’s native language is already C#)
• Also offers xaml support for creating user interface.

56.Why Xaml in Xamarin.Forms?

Ans:

• XAML(Extensible Application Markup Language.allows developers to define user interfaces in Xamarin.Forms applications using markup rather than code.
• XAML defines the visual appearance of a UI, and an associated code-behind file defines the logic. The UI design can be adjusted without necessarily making changes to the logic in code-behind. XAML in this role simplifies the workflow between individuals who might have a primary visual design responsibility and individuals who are responsible for app logic and information design.
• XAML(Extensible Application Markup Language.allows developers to define user interfaces in Xamarin.Forms applications using markup rather than code.
• XAML defines the visual appearance of a UI, and an associated code-behind file defines the logic. The UI design can be adjusted without necessarily making changes to the logic in code-behind. XAML in this role simplifies the workflow between individuals who might have a primary visual design responsibility and individuals who are responsible for app logic and information design.
• XAML cannot contain code. All event handlers must be defined in a code file.
• XAML cannot contain loops for repetitive processing. (However,ListView —can generate multiple children based on the objects in its ItemsSource collection.)
• XAML cannot contain conditional processing (However, a data-binding can reference a code-based binding converter that effectively allows some conditional processing.)
• XAML generally cannot instantiate classes that do not define a parameterless constructor. (However there is sometimes a way around this restriction.)
• XAML generally cannot call methods. (Again, this restriction can sometimes be overcome.)

57.What are the IDE’s we can use for Xamarin App Development?

Ans:

Xamarin Studio: This is Xamarin’s C# developer environment that runs on both Windows and Mac. Xamarin Studio has many of the features of Microsoft’s Visual Studio and uses exactly the same formats as Visual Studio: solutions (.sln.and C# projects (.csproj).Visual Studio: Xamarin offers a Visual Studio extension/plugin for visual studio 2012, visual studio 2013 update 1. And now Xamarin development is directly available from Visual studio 2015.

58.What was the major advantage of Xamarin Development?

Ans:

• We can deliver native iOS, Android, and Windows apps using existing skills, teams, and code(C#, xaml )
• We can take full advantage of Native API’s with Xamarin Technology . And Xamarin.Forms elements map to native controls and behaviors
• Xamarin Component Store allows adding high-quality components to your app directly from your IDE, including controls, web service APIs and more.
• PCL/ Shared projects makes very easy for developers to share the same code base across different projects.

59.What are difference between Xamarin Studio and Visual Studio?

Ans:

Notes:

• We can’t create Windows Phone, Windows & UWP from Xamarin Studio.
• Xamarin Studio in Mac can allows you to develop iOS & Android apps.
• Xmarin Studio in Windows can allows you to develop Android apps only. And it encourage Windows users to move to Visual Studio.
• Xamarin for Visual Studio supports any VS 2015, VS 2013 Update 2 and Visual Studio 2012 with non-Express editions. And visual studio can’t install on Mac machine.
• To test iOS app on Windows OS with VS, must be a Mac computer accessible on same network.
• To develop Xamarin.Forms apps for the Universal Windows Platform (UWP.requires Windows 10 with Visual Studio 2015

60.What are the life cycle’s of Xamarin.forms app development?

Ans:

Life-Cycle means a specific sequence of the application from start to finish of the application. So there are three important states in the life cycle of a Xamarin app development.

• OnStart: Called when the application starts.
• OnSleep: Called each time the application goes to the background.
• OnResume: Called when the application is resumed, after being sent to the background.

61.How many ways we can create Xamarin applications?

Ans:

There are two ways to deliver native iOS, Android, and Windows apps using Xamarin Technology

• Traditional Xamarin approach: This approach can provide direct access to platform-specific API’s. And we can create platform specific apps such as using Xamarin.iOS for iOS applications, using Xamarin.Android we can create Android applications.
• Xamarin.forms: This architecture is the same as that of traditional cross-platform apps. The most used method is to implement Portable Libraries or Shared Projects to save the shared code, and then create specific applications for each platform that will consume this shared code. 

62.When to use Xamarin.Forms vs Xamarin Native?

Ans:

Xamarin.Forms:

• Apps that require little platform-specific functionality.
• Apps where code sharing is more important than custom UI.

Xamarin.IOS,Xamarin.Android:

• Apps that require specialized interactions.
• Apps with highly polished design.
• Apps that use many platform-specific APIs.
• Apps where custom UI is more important than code sharing.

63.What are different extension output files generated from xamarin.forms?

Ans:

If we run the Xamarin app, it can generate following application packages for different platforms

• .xap/.Appx for windows phone 8, Windows, UWP
• .ipa file for IOS
• .apk file for Android

64.What are the different application package running modes in Xamarin?

Ans:

 When you compile an application, you usually choose between below two modes:

• Debug: Debug mode pads the executable file with extra information used for debugging purpose. After your application is bug-free and feature-complete, there’s no longer any need to keep the debug information.
• Release: Compiling in Release mode gives you a more compact (and even slightly faster.executable that doesn’t include unnecessary internal debugging symbols

Note: Packages should be in release mode, which would be provided to an App store.

65.How does Xamarin.Android(Mono for Android.work?

Ans:

On Android, Xamarin ships a fully functional implementation of the .NET runtime, called Mono, bundled with your app so that your code executes with all of the power of C# and .NET, including JIT-compilation, memory management, reflection, and the .NET base class libraries. Developers can use any native features by interacting with .NET class libraries that provide one-to-one mappings to all of the native APIs on Android.

66.What is the difference between Xaml & axml in Xamarin Technology?

Ans:

• AXML and XAML are two different XML specifications.
• AXML is just supported/available for Xamarin.Android.
• XAML is the way Xamarin Forms could standardize Cross Platform UI based on XML specification.
• XAML is the way Xamarin Forms could standardize Cross Platform UI based on XML specification.
• If you are using native Xamarin Android you will do UI using axml, if using Forms then using XAML.

67.How does Xamarin.IOS work?

Ans:

On iOS, Xamarin uses Mono, a fully functional implementation of the .NET runtime, to fully compile your app into a native ARM executable ahead of time (AOT.so that your code executes with all of the power of C# and .NET, including memory management, reflection, and the .NET base class libraries. Developers can use any native features by interacting with .NET class libraries that provide one-to-one mappings to all of the native APIs on iOS, while complying with Apple’s security restrictions which prevent execution of dynamically generated code on device.

68.What is the project structure of Xamarin.Forms?

Ans:

If we create App with xamarin.forms project using xamarin studio or visual studio. Then created project will have bellow structure:

• Shared: Shared Project containing the code common to all projects and it will be either PCL or Shared Project.
• AppAndroid: Xamarin.Android application project.
• AppiOS: Xamarin.iOS application project.
• AppWinPhone: Windows Phone application project.
• AppWindows: Windows application project.

AppUWP: Universal Windows Platform application project.

69.What are the different code sharing techniques in xamarin.forms?

Ans:

There are two alternative methods for sharing code between cross-platform applications:

• Portable Libraries(PCL)
• Shared Projects

The goal of a code-sharing strategy is to support the architecture, where a single codebase can be utilized by multiple platforms.