Introduction to Xamarin: The Complete Guide for Mobile App Development

As a mobile developer, you likely know the pain of building and maintaining separate native apps for iOS, Android, and Windows devices. It means juggling multiple programming languages, frameworks, and IDEs – not very efficient.

That‘s where Xamarin comes in. Xamarin is the rising star for building cross-platform native mobile apps with maximum code reuse. With over 1.4 million developers using it in 2018 and growing adoption by Fortune 500 companies, it‘s clear Xamarin is here to stay.

In this comprehensive guide, I‘ll provide you with a deep dive into the world of Xamarin development. I‘ll share everything you need – as an app developer – to evaluate if Xamarin is the right choice for your next mobile project.

By the end, you‘ll understand:

What Xamarin is and its key capabilities
Xamarin‘s architecture and how it works
The main advantages and tradeoffs of using Xamarin
How to get started building mobile apps with Xamarin
Power tips for leveraging Xamarin and .NET to the fullest

Let‘s get started demystifying this modern approach to cross-platform native mobile development.

What Exactly is Xamarin?

Xamarin is an open-source platform created by Microsoft for building high-performance native iOS, Android, and Windows apps using C# and the .NET framework.

With Xamarin, you can use C# to build mobile apps directly compiled to native assembly code. This gives the full power and performance of true native apps, unlike hybrid tools like React Native or Cordova.

Here are some key capabilities:

Build fully native iOS, Android and Windows apps with native UI and full access to APIs
Use C# and .NET to share code across platforms
Single IDE (Visual Studio) to develop apps across devices
Compile directly to native CPU instructions for maximum performance
Integrate with native SDKs and tools for each platform
Modern language features like async/await, LINQ, and more

In summary, Xamarin combines the performance of native with the productivity of code sharing.

As a developer, this means you can use your existing C# skills to build for mobile much faster without context switching. Companies can leverage existing .NET code and teams to go mobile. It‘s a big win for developer productivity and organizational alignment.

A Brief History of Xamarin and Mono

To understand Xamarin, you need to know a bit about its origins in the Mono open source project. Here‘s a quick timeline:

2001: Mono project founded by Miguel de Icaza to port .NET to Linux/Mac
2011: Xamarin company created by Mono developers to build mobile dev tools
2013: First releases of Xamarin.iOS and Xamarin.Android
2016: Microsoft acquires Xamarin as part of its .NET strategy
2016: Xamarin SDKs become open source under the .NET Foundation

So in summary, Xamarin was born out of the need to bring C# and .NET developers into mobile app development through the Mono project. It has now evolved into a mature mobile dev stack led by Microsoft and the .NET community.

An important takeaway is that Xamarin is not a lock-in to Microsoft tools. It is open source and cross-platform by design. This gives enterprise developers confidence to adopt Xamarin for the long haul.

Is Xamarin Right For Your Mobile App Project?

Given its capabilities, who is Xamarin best suited for? Here are some of the common profiles I see making the most of Xamarin:

C# developers looking to build mobile apps without new languages
.NET shops with existing systems who want mobile frontends
Companies migrating desktop apps to mobile on Windows, iOS and Android
Teams building cross-platform mobile apps targeting enterprises
Developers seeking maximum code reuse across mobile OSes

Based on my experience, these types of developers and teams get the most benefits from Xamarin‘s mix of native performance and cross-platform productivity.

Of course, Xamarin has a learning curve for non-.NET developers. But the code reuse savings add up quickly for companies targeting multiple mobile platforms.

For consumer apps requiring pixel-perfect custom UIs, native SDKs may be a better choice. But even then, many apps use Xamarin.Forms for the core app and native SDKs for bespoke screens.

Understanding the Xamarin Architecture

From a high-level architecture standpoint, how does Xamarin actually work? What‘s happening behind the scenes when you build mobile apps with it?

Here is a quick overview:

Xamarin architecture diagram

Xamarin apps use C# and .NET libraries for core business logic and data access
The UI layer can be built with Xamarin.Forms for code sharing or native SDKs for platform-specific UIs
C# code gets compiled down to Intermediate Language (IL) bytecode that is portable across OSes
At runtime, the IL code is Just-in-Time (JIT) compiled to native CPU instructions for maximum performance

By using IL as an intermediary format, Xamarin gets the best of both worlds:

Write code in C# once and run anywhere
Apps still compile directly to native assembly for each target platform

This is the key to how Xamarin delivers both code portability and native performance – a rare mix in the mobile dev world.

The Key Benefits of Choosing Xamarin

Given how it works, what are the unique benefits Xamarin can offer for your mobile projects?

Native Performance

Xamarin apps render using native controls and compile directly to native assembly code. They have the same smooth UI performance and direct hardware access as apps built totally natively in Swift or Java.

With .NET Standard libraries and shared app logic, Xamarin allows huge code reuse across iOS, Android and Windows. This can massively cut development and maintenance costs.

Single Language and IDE

Developers can use C# with Visual Studio to build apps for all mobile platforms. It‘s all the same IDE experience and avoids context switching.

Access to Native APIs and Tools

Xamarin provides access to all the native platform SDKs like Android SDK and iOS SDK. Developers aren‘t limited at all in what APIs they can access.

Modern and Versatile Programming Language

C# is an elegant object-oriented language with amazing features like LINQ, async/await, tuples, pattern matching, and more.

Enterprise App Development

Xamarin works great for large dev teams and mission-critical LOB mobile apps. Microsoft shops embrace it.

Microsoft Ecosystem Integration

It integrates tightly with Azure, Office 365, Power BI, and other Microsoft services.

For developers with Microsoft experience, Xamarin feels like an easy transition into cross-platform mobile dev. The C# skills transfer over.

How to Get Started with Xamarin

If you want to start building mobile apps with Xamarin, here is an overview of what‘s involved:

Step 1: Install Visual Studio

You‘ll need to install Visual Studio 2019 or 2022. Make sure to choose the Mobile development with .NET workload.

Step 2: Setup Emulators

Configure emulators for iOS and Android to test your apps. Use the Android emulator bundled with Visual Studio. For iOS, use MacInCloud or real Mac hardware.

Step 3: Create Your First App

Use the built-in app templates in Visual Studio to create a basic "Hello World" app using Xamarin.Forms.

Step 4: Build the UI

Use Xamarin.Forms or native SDKs to construct your user interface and views. Xamarin.Forms provides the most code reuse.

Step 5: Add Business Logic

Use C# and .NET to implement the underlying business logic, data layers, and platform-specific code.

Step 6: Debug and Test

Debug and test your app locally using Visual Studio‘s built-in emulators. Then deploy to real devices for final testing.

Microsoft has done an excellent job simplifying the getting started process. You can build your first app in minutes.

Choosing Between Native SDKs and Xamarin.Forms

Once you start building apps, you‘ll have to decide whether to use the native SDKs or Xamarin.Forms for the UI code. Here are some guidelines:

Native SDKs

Ultimate flexibility and control over UI
Access to newest OS features and APIs
Best performance – compiled directly to native
Consistent look and feel per platform

Xamarin.Forms

Maximize code reuse across platforms
Build UI with C#/XAML instead of Swift/Java/Kotlin
Single UI framework to learn
Simpler maintenance with shared UI code
Limited customization compared to native UIs

In general, use native SDKs when you require fine-grained control and customization. Use Xamarin.Forms when code reuse is critical.

Many apps take a hybrid approach, using Xamarin.Forms for the core UI and native SDKs for bespoke screens. This balances both worlds.

Leveraging Xamarin.Forms for Cross-Platform UI

For teams focused on code reuse, Xamarin.Forms is an incredibly useful tool for building cross-platform UI:

Write UI in C# and XAML instead of platform languages
UI code is shared but still compiled to fully native apps
Mobile-first UI framework modeled after XAML patterns
Provides views for navigation, pages, layouts, controls and more
Drop down to native SDKs for platform-specific features

Xamarin.Forms is the "sweet spot" – maximizing code reuse without compromising the benefits of native apps.

This allows small teams or individuals to build mobile apps for iOS and Android faster than ever before. For larger teams, it still reduces redundant work on UIs across platforms.

Top Xamarin and .NET Libraries to Know

The .NET ecosystem supports Xamarin with many high-quality libraries:

MVVM Frameworks – MVVM Light, FreshMvvm, Prism
Networking – Refit, Polly, HttpClientFactory
Serialization – Newtonsoft.Json, Protobuf, ServiceStack.Text
DI Containers – Autofac, DryIoc, Ninject
Data Access – Dapper, Entity Framework Core
Testing – NUnit, Moq, FluentAssertions

With Microsoft‘s NuGet package manager, integrating these libraries is seamless. This gives C# developers a huge advantage in Xamarin productivity.

How Xamarin Compares to Alternatives

Xamarin occupies a unique middle ground between pure native development with Swift/Java/Kotlin and hybrid cross-platform tools like React Native, Flutter and Ionic.

Compared to React Native and others, it delivers much better performance by compiling directly to native. But this comes at the cost of less flexible UIs.

Compared to fully native development, Xamarin provides massive productivity gains through code sharing – but doesn‘t support new OS features quite as quickly.

There are always tradeoffs. But by combining native with cross-platform, Xamarin hits a sweet spot many developers love.

Walkthrough: Building a Simple Xamarin "Hello World" App

To see Xamarin in action, let‘s walk through a simple "Hello World" app:

Create a new Xamarin.Forms app in Visual Studio using the Blank Forms template
Open MainPage.xaml and add a Label widget:

<Label Text="Hello Xamarin!" VerticalOptions="Center" HorizontalOptions="Center" />

Run the app in the Android emulator – the label text renders as native Android!
Try changing the text color to red and re-running – changes appear instantly.

This quick example shows how we can build a cross-platform UI in XAML and C# that compiles to native controls – pretty cool!

Key Takeaways on Xamarin and its Benefits

Here are the major points:

Build native iOS, Android and Windows apps in C#/.NET
Maximize code reuse while keeping native performance
Use familiar tools like C# and Visual Studio on Mac and PC
Integrate with native APIs and SDKs for full access
Xamarin.Forms enables cross-platform UI code sharing
Perfect for Microsoft shops and .NET developers

For companies using Microsoft tools, Xamarin unlocks huge productivity gains for mobile.

C# developers can use their existing skills to build for mobile faster than ever before. It‘s an easy on-ramp.

Top Resources for Learning Xamarin

To take your Xamarin skills to the next level, here are some amazing (and free) resources:

Xamarin University – Hands-on self-guided courses
Xamarin Documentation – Comprehensive developer docs
Xamarin Forums – Ask questions and discuss
YouTube – Video tutorials
Planet Xamarin – News/blogs
Xamarin Certification – Prove your expertise

For paid training, I recommend the Xamarin courses on Pluralsight and Udemy. They are incredibly high-quality and regularly updated.

Final Thoughts on Xamarin and Cross-Platform Mobile Development

Xamarin solves major pain points in cross-platform mobile dev:

Use C# to build for iOS, Android and Windows
Share significant code across platforms
Maintain one codebase and toolchain
Leverage existing .NET skills and systems
Access full native capabilities and performance

These strengths make Xamarin a top choice for Microsoft-centric organizations going mobile. It also empowers small teams and individuals to build mobile apps faster and cleaner.

However, Xamarin isn‘t a silver bullet. Developers still need native platform expertise to build quality apps. And leveraging native APIs fully requires escaping cross-platform abstractions at times.

But on the whole, Xamarin moves the bar significantly forward. The progress in mobile dev productivity in recent years is astounding.

My advice: the next time you or your team starts a mobile project, take Xamarin for a test drive. You may be surprised and delighted by what it can enable.

I hope this guide gave you a solid foundation on Xamarin and how to leverage it for your mobile apps. Let me know if you have any other topics you‘d like me to cover!