Xamarin for (not only) Android developers

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Xamarin for not only Android developers Aleksander Piotrowski @pelotasplus

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What platform needs to be a rockstar platform

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IDE Visionary Documentation Jake Wharton Testing tools/services Emulator Third-party components Library Events Blogs/podcasts Programing Language

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History a rising star

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2000 Microsoft announces .NET Framework 2001 Mono project launched by Ximian 2003 Ximian bought by Novell 2004 Mono first release 2009 MonoTouch 1.0 2011 MonoAndroid first release 2011 Novell acquired by Attachmate 0000 Xamarin is founded 2012 Xamarin.Mac 2013 Xamarin Studio .NET is 15 years old mono is 11 years old Xamarin.iOS is 7 years old Xamarin.Android is 4 years old modern Xamarin is 2 years old

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Miguel de Icaza ● never received a degree ● free software developer since 1992 ● Midnight Commander ● early Wine contributor ● worked on Linux Sun SPARC ● later on Linux for SGI Indy ● almost did Internet Explorer port to SPARC ● started GNOME project and created Gnumeric ● started Mono project to implement .NET on Linux source: wikipedia

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source: wikipedia

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Pricing not free for personal use

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command line support good IDE x2 if targeting both iOS and Android

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Write once run everywhere* * that to run your app on every device make sure it contains nothing else but white background without any other UI elements

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Supported platforms ● target: ○ Android, iOS, Mac ○ Windows Phone by sharing C# code between projects ● development: ○ Mac: for all platforms excluding Windows ○ Windows: for all platforms by using remote Mac ○ Linux: -

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What is ● single language for all platforms - C# ● single base library - .NET Base Class Library plus specific libraries for target platforms MonoTouch or Mono.Android ● single runtime for all targeted platforms iOS, Android, Windows Phone ● “performant enough even for demanding games”

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What is not ● write once and run anywhere ● use one one platform (Mac or Windows) to target them all (iOS, Android, Windows) ● one UI for all target platforms

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Native vs non-native iOS ● native code at the end ● AOT compiler converts Xamarin app to native ARM code Android ● no final native code ● Xamarin compiler creates IL (Intermediate Language) which is executed at runtime on the device

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Fat binary vs slim debug build ● Hello world + Base Class Library: 15.8MB ● Hello world + BCL after Linking: 2.9MB ● Hello world debug release: 6KB + Mono Shared components: 10MB source: used to be here http://developer.xamarin.com/guides/android/advanced_topics/linking/

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IDE one to rule them all

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IDE ● have to switch manually between iOS and Android in multiplatform projects ● ultra annoying “app is running, are you sure you want to stop it and install new version?” ● cannot compare to IntelliJ aka IDEA ● Visual Studio to the rescue ● overriding methods CMD-I

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Let’s code and have fun hopefully

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Let’s code in C# and F# var i = 10; // implicitly typed int i = 10; // explicitly typed #define preprocessor directive ulong, ushort unsigned types async/await for asynchronous programming mandatory break in switch Lambda expression Generics with runtime type support namespaces properties

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Let’s code in Java or Objective-C ● using Java Native Interface (JNI), or ● using bindings for Java code ● with Objective-C creating binding ● straightforward process, for the second time

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Project^wSolution structure

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Solution structure ● References - base .Net classes ● Components ● Packages ● Assets ● Properties ● Resources ● our code ● and even maybe tests...

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Code sharing

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Layers ● Data Layer SQLite ● Data Access Layer create, read, update, delete ● Business Logic data model and business logic ● Service Access Layer access REST, parsing JSON ● Application Layer platform specific code but not UI-related ● User Interface Layer UI-related code shared not shared shared shared shared not shared

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source: https://xamarin.com/forms

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Code Sharing ● Shared Project ● Portable Class Library

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Shared Project ● no .dll as an output ● “compiled into” referencing project ● not compiled, if not used ● platform specific code via #if statements ○ #if __MOBILE__ ○ #if __ANDROID__ ● “for personal use only”

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source: http://developer.xamarin.com/guides/cross-platform/application_fundamentals/shared_projects/

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Portable Class Library ● using a subset of BCL called Profile ● targets many different (supported) platforms ● no platform-specific libraries allowed ● refactoring of PCL affects all referencing projects ● good for sharing with others

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source: http://developer.xamarin.com/guides/cross-platform/application_fundamentals/building_cross_platform_applications/sharing_code_options/

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source: http://developer.xamarin.com/guides/cross-platform/application_fundamentals/building_cross_platform_applications/sharing_code_options/

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UI design

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Xamarin Forms

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source: https://xamarin.com/forms

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source: video @ https://xamarin.com/forms

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Forms ● single app screen called a Page ● Page contains layouts (StackLayout, GridLayout) and UI elements (Button, Image, SearchBar, WebView) ● connect actions (click event, long press event) to code which is shared across all platforms ● at the end at run-time all UI elements are mapped to native platform- specific UI components

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Forms ● can be written in pure code ○ sounds a bit like old school iOS style ● or in XAML layout files ○ sounds more like Android style ○ not supporting existing XAML editor :-/ ○ layouts have supporting class, so called CodeBehind class ● using MVVM pattern

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source: https://xamarin.com/forms

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source: https://xamarin.com/forms

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source: https://xamarin.com/forms

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source: https://xamarin.com/forms

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Pros ● data entry apps ● prototypes & proof-of- concept apps ● little platform-specific APIs ● code sharing over custom UI Cons ● specialized interaction required ● highly polished design ● many platform- specific APIs ● custom UI above code sharing

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Emulator or is it simulator

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Xamarin Player ● simulate, debug, demo or run Android apps in our fast and hassle-free environment. only Android apps ● integrated with Xamarin Studio and Visual Studio ● native UI on Windows and Mac ● widgets for location and battery ● easy screenshot taking

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Xamarin Player ● x86 virtual machine with HW acceleration ● VT-x AMD-V ● OpenGL 2.0 ● uses VirtualBox 5.0.4

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Xamarin Player ● can install non-Xamarin native Android APKs? YES ● supports Google Play Services? YES via installing third-party provided ZIP file ● hmm, sounds like a Genymotion clone? YES indeed

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Xamarin Player ● free ● less widgets ● better drag & drop ● fixed aspect window scaling ● couple of device configurations ● paid ● more widgets ● drag & drop ● window scaling ● lots of device configurations

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Documentation for C#, Android, iOS, and ...

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Documentation ● for all targeted platforms Xamarin.Android, Xamarin.iOS, Xamarin.Forms, Xamarin.Mac and Windows ● Android developer could learn iOS app architecture ● explains not only C# or Xamarin-related aspects but also basics of the platforms ● always with “download as PDF”

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Documentation ● iOS app fundamentals http://developer.xamarin.com/guides/ios/application_fundamentals/ Protocols, Events, and Delegates ● iOS user interface http://developer.xamarin.com/guides/ios/user_interface/ UIKit, Tables and cells, Storyboards ● platform features http://developer.xamarin.com/guides/ios/platform_features/ Newsstand, HealthKit, and iOS 9 introduction

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Documentation ● Android app fundamentals http://developer.xamarin.com/guides/android/application_fundamentals/ API levels, Activity lifecycle, Handling rotation ● Android user interface http://developer.xamarin.com/guides/android/user_interface/ Actionbar, Splash screen, List view & adapters, RecyclerView ● platform features http://developer.xamarin.com/guides/android/platform_features/ Fragments, ContentProvider, new Android versions

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Third-party libraries maven, pip, apt, cocoapods, npm, we want more!

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Third-party libraries ● components via Xamarin Components Store ● packages via NuGet package manager ● libraries & UI components ● easily to be added to a project

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Components ● HockeyApp ● Crittercism ● SQLCipher 499$ ● Facebook SDK by Xamarin Inc. ● Parse SDK by Parse Inc. ● Tip of the Day

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Packages ● for Android, iOS, or both ● native C# ● via NuGet packages by .NET Foundation ● 44,015 packages

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Packages ● Android Support Library, Design Library, RecyclerView by Xamarin ● Android Picasso by jacksierkstra ● iOS SVProgressHUD (wrapper) ● iOS FloatLabelEntry (native) ● Parse.com in 6 versions

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Packages ● get data from RESTful API and store it in data model ● refit by paulcbetts ● one C# code for Android, iOS and .NET RESTful API data model network service in our app AFNetworking Retrofit Retrofit manually as a dict

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Packages ● get data from network ● iOS AFNetworking ● Android OkHttp latest is 2.5.0 ● Xamarin ModernHttpClient on iOS NSURLSession on Android OkHttp 2.4.0

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Testing in case you have time for that

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Testing ● Xamarin Test Cloud ● Calabash

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Xamarin Test Cloud ● 1,800 devices and adding 100 monthly ● stars at 1,000 USD/month paid annualy … for 2 apps ● 5,000 USD for 5 apps ● NUnit or Calabash tests ● screenshots, device performance for every step of every test

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source: https://xamarin.com/test-cloud

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source: https://xamarin.com/test-cloud

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Calabash ● automated UI tests ● using Behavior Driven Development approach ● written in Ruby, or Cucumber, or Gherkin

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source: http://developer.xamarin.com/guides/testcloud/introduction-to-test-cloud/

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Scenario: Credit card number too short Given I am on the Credit Card Validation Screen When I enter a credit card number that's 16 digits long And I click on the Validate button Then I should see a validation error source: http://developer.xamarin.com/guides/testcloud/calabash/introduction-to-calabash/

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Community and expensive conference

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Community ● blogs ● developer advocates and their apps James Montemagno https://github.com/jamesmontemagno ● podcast - Xamarin Podcast http://pca.st/9cXF ● their own WWDC, also quite pricey 1,499$ Xamarin Evolve ● Paul C. Betts and his libraries https://github.com/paulcbetts/

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IDE Visionary Documentation Jake Wharton Testing tools/services Emulator Third-party components Library Events Blogs/podcasts Programing Language

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IDE Visionary Documentation Jake Wharton Testing tools/services Emulator Blogs/podcasts Third-party components Library Events Paul C Betts Xamarin Studio Xamarin Podcast Miguel de Icaza Documentation Evolve Xamarin Android Player Components & packages Test Cloud & Calabash Programing Language C#, F#, support native

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