Cross platform mobile developmentwith Visual Studio and Xamarin: Architecture and code reuseIbon Landa

Plain Concepts

Native Development

iOS

Objective C

Xcode

Windows Phone

C#/Visual Basic/F#

Visual Studio

Android

Java

Eclipse

IntelliJ

Using the platform native tools

Xcode ADT Visual Studio

+

+

-

✗

Build and debug iOS applications on a Windows computer using the Visual Studio IDE

Windows

Windows 7 or higher.

Visual Studio 2010 Professional or higher.

Xamarin’s plug-in for Visual Studio.

MAC

A Macintosh running OS X Lion or higher (although we recommend the latest version).

Xamarin iOS SDK.

Apple’s Xcode IDE and iOS SDK (we recommend the latest version from the App Store).

Xamarin.iOS on Windows

Xamarin.iOS on Windows

Use PCLs

Use View Models to reuse presentation code

Heavy use of dependency injectionAllows different implementations for different platforms

Improving Code Reuse in 3 easy ways

Create a single library that can be used by multiple .net frameworks

Allows access only to functionality shared by all selected frameworks

Does some nifty namespace mapping

Makes cross platform development much easier

Microsoft and 3rd party PCLs available (HttpClient, Imaging, JSON…)

Portable Class Libraries

Shared Core

Maximizing code reuse

How to display information

What information to display

Flow of interaction

Data objects

Business logic

Etc.

Model

View Model

View Device-specific

Portable codeReferences

Databinds

UI

Application Logic

Out of the box approach

View

ViewModel

Model

Model-View-ViewModel (MVVM)

Cross Platform MVVM Development Framework

Free, open source

SupportsWP7,8WPFWinRTXamarin.AndroidXamarin.iOSXamarin.Mac

AKA Mvx

MvvmCross

XAML Code

<StackPanel><TextBox Text="{Binding Hello, Mode=TwoWay}" /><TextBlock Text="{Binding Hello}" /><Button Content="Click Me" Command="{Binding MyCommand}" /><Button Content="Go Second"

Command="{Binding GoSecondCommand}"/>

</StackPanel>

public class FirstViewModel : MvxViewModel{

private string _hello = "Hello MvvmCross";public string Hello{

get { return _hello; }set { _hello = value; RaisePropertyChanged(() => Hello); }

}

public System.Windows.Input.ICommand MyCommand{

get{

return new Cirrious.MvvmCross.ViewModels.MvxCommand(DoMyCommand);}

}

private void DoMyCommand(){

Hello = Hello + " World";}

public System.Windows.Input.ICommand GoSecondCommand{

get{

return new Cirrious.MvvmCross.ViewModels.MvxCommand(DoGoSecond);}

}private void DoGoSecond(){

ShowViewModel<SecondViewModel>();}

}

MvvmCross Architecture

Convenient way to access platform functionality

Use NinjaCoder or Nuget to add plugins

Includes Accelerometer, Email, Files, Location, Messaging, Sqlite

3rd party plugins available as well.

Consume plugins using Dependency Injection or Service locator

MvvmCross Plugins

Describe functionality using an interface in .Core

Create platform specific implementation in .xxxx

Register implementation on app startupMvx.RegisterSingleton<ISettingsPersistance>(new SettingsPersistanceWPF());

Mvx.RegisterType<IGetRemoteData, RemoteDataWpf>();

Consume plugins using Dependancy Injection or Service locatorpersistance = Mvx.Resolve<ISettingsPersistance>();

Platform specific code

Architecture overview

PCLs let you use easily share code across multiple platforms

Xamarin lets you use C# on Android, iOS and Mac

MvvmCross wraps it all up to make it easyShared PCL that holds most functionality

Platform specific apps for views and dependant code

Plugins let you easily add functionality in a cross platform friendly way

Do your own platform dependant stuff using interfaces and IoC/Dependancy Injection

Summary

Thanks!