Xamarin Forms, MVVM and Testing

Speaker

Basic(1989)

C(1991)

C++(1997)

Java(1997)C#(2005)

JavaScript(2008)

Others Languages

with Xamarin Forms

for 8 Months

iOS

with Xamarin Forms

for 3 Weeks

Android

Xamarin

C# 3.0 (2007)Java 8 (2014)

C# 5.0 (2013)

C# 4.0 (2010)

Lambda

Expression Trees

LINQ

Lambda

Streams

Dynamic

Asynchronous

Native

• Native User Interfaces

• Native API Access

• Native Performance

Xamarin Forms

App Logics

Cross-platform Natively Backed UI

Platform-specific API

iOS

Platform-specific API

Android

Platform-specific API

Windows Phone

XAML

• Extensible Application Markup Language

• XML

• WPF(2006)

• 2-way Binding

• Data Templating

Model View ViewModel

MVVM(Model-View-ViewModel)

• In 2005, John Gossman(Microsoft)

• A Variation of MVC

• Separation of Presentation and Presentation Logic

• 2-way Binding

• Testability

• WPF, Silverlight, Xamarin Forms, AngularJS, EmberJS, KnockoutJS, RoboBinding

• Introduction to Model/View/ViewModel pattern for building WPF apps

• WPF Apps With The Model-View-ViewModel Design Pattern

ViewModel

• An Abstraction of a View

• State and Behavior

• Does not need a reference to a view

ViewModel

Presentation Logic

View

User Interface

Model

Business Logic and

Data

2-way Binding

Unit Testing

Unit Testing

Pros

• Cheap

• Finds problems early

• Living Documentation

• As a Design Element

Cons

• Not catch integration errors

• Not catch system-level errors

• Can’t write for user interfaces

Presentation Layer

View(UI)

ViewModel(Presentation Logic)

• No Reference to Views

• No Lifecycle Constraint

Testable

Bindings

Bindings

• Properties

• Collections and Templating

• Commands

Properties

<Entry Text="{Binding NameEntry}" />

Collections and Templating

<ListView ItemsSource="{Binding Users}">

<ListView.ItemTemplate>

<DataTemplate>

<ViewCell>

<Label Text="{Binding Name}" />

</ViewCell>

</DataTemplate>

</ListView.ItemTemplate>

</ListView>

Commands

<Button Command="{Binding Add}" />

Events

Events

• PropertyChanged

• CollectionChanged

• CanExecuteChanged

Properties

• INotifyPropertyChanged

• PropertyChanged

Collection

• INotifyCollectionChanged

• CollectionChanged

Commands

• ICommand

• CanExecute

• CanExecuteChanged

Summary

Xamarin

• C#

• Native

• Visual Studio

• Designer

Xamarin Forms

• Cross-platform Natively Backed UI

• XAML

• 2-way Binding

• Data Templating

MVVM

• Separation of Presentation and Presentation Logic

• 2-way Binding

• Testability

• Property, Collection, Command

• PropertyChanged, CollectionChanged, CanExecuteChanged