In this session we introduced the MvvmCross open source framework for Xamarin and talk about how can it help you build clean and polished apps without compromise. It doesn’t matter if you use traditional Xamarin or Xamarin.Forms (spoiler: MvvmCross supports both!). Some of the topics include: - MVVM pattern - Why to use an MVVM framework? - IoC, DI - Data Bindings - Converters - Navigation - ViewPresenters - And more!

1. Xamarin & MvvmCross
in depth
Nicolas Milcoff (aka @nmilcoff)
Microsoft MVP - MvvmCross Maintainer

2. Agenda
▣ MVVM pattern recap
▣ Why to use an Open Source MVVM framework?
▣ MvvmCross
▣ Framework goodies
▣ Demos
▣ Q & A

3. The MVVM Pattern

4. MVVM benefits
▣ Highly decoupled components
▣ Code sharing ++
▣ Scalability
▣ Working in parallel made easy
▣ Stable and proven pattern

5. Open Source (MVVM) Frameworks
▣ Abstractions discussions --
▣ Barriers for new developers --
▣ Requirements focus ++
▣ Time saving ++
▣ Inputs from multiple developers / teams ++

6. App development
without compromise

7. MvvmCross

8. Supported Platforms
▣ Xamarin.Android, Xamarin.iOS
▣ Xamarin.Mac, Xamarin.tvOS
▣ UWP, WPF
▣ Tizen (WIP)
▣ Console!
▣ Xamarin.Forms

9. Features in a nutshell
▣ ViewModel first Navigation
▣ Data Bindings, Commands and Converters
▣ IoC Container / DI engine
▣ Platform specific widgets
▣ Unit Test Helpers
▣ Plugins
▣ Complete flexibility!

10. ViewModels
▣ Implement INotifyPropertyChanged
▣ Lifecycle:
□ void Prepare(MyObject parameter)
□ Task Initialize()
□ void Appearing(), void Appeared()
□ void Dissapearing(), void Dissapeared()
□ void ViewDestroyed()
□ void SaveStateToBundle(IMvxBundle bundle)
□ void ReloadFromBundle(IMvxBundle bundle)

11. Navigation in MvvmCross

12. Navigation in MvvmCross
▣ All logic remains in the shared code
▣ ViewPresenters for each platform
▣ Presentation attributes for declaration
▣ Presentation Hints for behavior
▣ 100% customizable

13. Navigation in MvvmCross
public class RootViewModel : MvxViewModel
{
private readonly IMvxNavigationService _navigationService;
public RootViewModel(IMvxNavigationService navigationService)
{
_navigationService = navigationService;
}
private async Task OpenModalAsync()
{
await _navigationService.Navigate<ModalViewModel>();
}
}

14. Navigation in MvvmCross
[MvxContentPagePresentation(WrapInNavigationPage = true)]
public partial class RootPage : MvxContentPage<RootViewModel>
{
// your code
}
[MvxModalPresentation]
public partial class ModalPage :
MvxContentPage<ModalViewModel>
{
// your code
}

15. DEMO!
Navigation & ViewPresenters

16. Data Bindings in MvvmCross
▣ Support for .cs, .xml, .axml, .xaml
▣ Value Converters
▣ Value Combiners
▣ OneWay, TwoWay, OneWayToSource, OneTime
▣ Multiple syntaxes
▣ Support for custom bindings

17. Data Bindings in MvvmCross
▣ Bindings in .axml (Tibet):
local:mvxBind=“Text MyTextProperty”
local:mvxBind=“Click MyAwesomeCommand”
local:mvxBind=“Checked Inverse(Prop), Mode=TwoWay,
Fallback=False”

18. Data Bindings in MvvmCross
▣ Bindings in xaml (Tibet):
mvx:Bi.nd="Text MyTextProperty”
mvx:Bi.nd=“Click MyAwesomeCommand”
mvx:Bi.nd=“Checked Inverse(Prop), Mode=TwoWay,
Fallback=False”

19. Data Bindings in MvvmCross
▣ Bindings in .cs (Fluent):
set.Bind(MyLabel).For(v => v.Text).To(vm => vm.MyProperty);
set.Bind(MyButton).To(vm => vm.MyAwesomeCommand);
set.Bind(MySwitch)
.For(v => v.On)
.To(vm => vm.Prop)
.WithConversion<InverseConverter>()
.WithFallback(false);

20. DEMO!
Data Binding

21. IoC Container and DI engine
▣ It’s optional
▣ Service Locator / IoC
▣ Constructor and Property Dependency Injection
▣ Singletons, dynamics, Open Generics, Child
Containers
▣ Bulk registrations
▣ What if I prefer to use $Lib$ instead? Also possible!

22. IoC Container and DI engine
Source: https://xamarinhelp.com/ioc-container-performance/

23. DEMO!
IoC Container / DI Engine

24. Platform specifics
▣ Support for Android.Support packages
▣ Polymorphic lists made easy
▣ Support for background services / push
notifications
▣ iOS Side Menu
▣ Abstraction plugins for most common features

25. Plugins
▣ Small code pieces that resolve specific situations
▣ Install from NuGet -> Run
▣ Official Plugins: Accelerometer, Visibility, Json,
Color, Localization, Messenger, Email, …
▣ Loads of 3rd party plugins

26. DEMO!
Plugins

27. Resources & Documentation
mvvmcross.com
Where our official
documentation lives
github.com/MvvmCross
Official samples and
source code
Slack
xamarinchat.herokuapp.
com. Then join
#mvvmcross
StackOverflow
Ask using the
#mvvmcross tag
Xamarin Forums
Use the official forums
Twitter
Follow and don’t
hesitate to contact
influencers

28. Get involved!
Support us on
OpenCollective
Contribute on
GitHub
Blog about your
experiences
Use the framework
in your apps

29. Questions?

30. Thanks!
Nico Milcoff
@nmilcoff
nicolas.milcoff@d-genix.com