This document discusses Xamarin Forms, MVVM design pattern, and testing. It covers how Xamarin Forms allows building cross-platform mobile apps using C# and XAML that are natively backed. It also describes the MVVM pattern which separates presentation and logic for testability using bindings, properties, collections and commands. Events like PropertyChanged, CollectionChanged, and CanExecuteChanged are used to notify views of changes.

1. Xamarin Forms, MVVM and Testing

2. Speaker

5. Basic(1989)
C(1991)
C++(1997)
Java(1997)C#(2005)
JavaScript(2008)
Others Languages

6. with Xamarin Forms
for 8 Months
iOS
with Xamarin Forms
for 3 Weeks
Android

8. Xamarin

11. C# 3.0 (2007)Java 8 (2014)
C# 5.0 (2013)
C# 4.0 (2010)
Lambda
Expression Trees
LINQ
Lambda
Streams
Dynamic
Asynchronous

12. Native
• Native User Interfaces
• Native API Access
• Native Performance

15. Xamarin Forms

16. App Logics
Cross-platform Natively Backed UI
Platform-specific API
iOS
Platform-specific API
Android
Platform-specific API
Windows Phone

17. XAML
• Extensible Application Markup Language
• XML
• WPF(2006)
• 2-way Binding
• Data Templating

20. Model View ViewModel

21. 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

22. ViewModel
• An Abstraction of a View
• State and Behavior
• Does not need a reference to a view

23. ViewModel
Presentation Logic
View
User Interface
Model
Business Logic and
Data
2-way Binding

24. Unit Testing

25. 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

26. Presentation Layer
View(UI)
ViewModel(Presentation Logic)
• No Reference to Views
• No Lifecycle Constraint
Testable

27. Bindings

28. Bindings
• Properties
• Collections and Templating
• Commands

29. Properties
<Entry Text="{Binding NameEntry}" />

30. Collections and Templating
<ListView ItemsSource="{Binding Users}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Label Text="{Binding Name}" />
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>

31. Commands
<Button Command="{Binding Add}" />

32. Events

33. Events
• PropertyChanged
• CollectionChanged
• CanExecuteChanged

34. Properties
• INotifyPropertyChanged
• PropertyChanged

35. Collection
• INotifyCollectionChanged
• CollectionChanged

36. Commands
• ICommand
• CanExecute
• CanExecuteChanged

37. Summary

38. Xamarin
• C#
• Native
• Visual Studio
• Designer

39. Xamarin Forms
• Cross-platform Natively Backed UI
• XAML
• 2-way Binding
• Data Templating

40. MVVM
• Separation of Presentation and Presentation Logic
• 2-way Binding
• Testability
• Property, Collection, Command
• PropertyChanged, CollectionChanged, CanExecuteChanged