c# everywhere - building cross-platform apps with xamarin and mvvmcross
TRANSCRIPT
Building Cross-Platform Apps with Xamarin and
MvvmCrossFlavius-Radu DEMIAN
A bit about me
• General Manager@Deventure
• Timisoara .Net Meetup organizer
• Mobile and Web developer
• Xamarin and Umbraco enthusiast
• In love with technology
[email protected] @flaviusdemian
Agenda
Mobile Development ApproachesXamarin’s Unique ApproachThe Xamarin Magic How it Works on iOSHow it Works on AndroidCode Sharing Techniques
Agenda
What is MVVM?Why MVVM?The MvvmCross magic Data-Binding, Commands, NavigationAdvantagesDisadvantages
Expectations
I wish to have an interactive presentation.Please feel free to ask questions any time.
After this presentation, you should know:• what Xamarin is and how to use it• the advantages and disadvantages of Xamarin• what is MVVM• what Mvvmcross is and how to use it
Expectations
My ultimate goal is to make you
curios.
Go home and try it yourself!
Mobile Development Approaches
Mobile Development ApproachesSilo Approach
Silo Approach
• each platform with it’s own stack – in it’s own silo• no code sharing• multiple teams => many developers• multiple codebase => synchronization problem• different toolsets
Mobile Development ApproachesWeb Approach
Web Approach“Write once, run anywhere”.
• no apps to deploy to the stores• shared codebase• basically a native app with a Webview• native look is simulated with CSS• most times you can tell it is written in HTML• fewer developers
Xamarin’s Unique Approach
Xamarin’s Unique Approach
Xama…what?
Xamarin Timeline
Xamarin’s Unique Approach
• native user interface• native performance• shared code across platforms• usage of C# & .NET framework• full API coverage• fewer developers
Xamarin’s Unique Approach
Probably the best way in a “Mobile First. Cloud First. People First” Satya Nadella
The Xamarin MagicWrite Everything in C#
The Xamarin Magic
.NET + iOS APIs100% coverage
The Xamarin Magic
.NET + Android APIs100% coverage
The Xamarin Magic
.NET + Windows APIs
The Xamarin MagicXamarin takes the C# code and it compiles it down to native on iOS and Android.
The magic is that you can also use it on the Windows platform.
(Almost) everything you can do in Objective-C, Swift or Java can be also done in C# with Xamarin.Check the limitations on www.xamarin.com .
Since you use C# on all the platforms, code reuse varies from 60% to 90%.
JIT compilationAOT compilation
How Xamarin Works on iOS
iOS Build + Execution Model
• code runs as 100% native app
• full Ahead of Time (AOT) compilation to produce an ARM binary for Apple’s App Store
• Mono Framework included
• exposes CocoaTouch SDK
iOS Build + Execution Model
We can take advantage of the APIs exposed by Mono besides the fully covered iOS APIs.
Since we have Mono involved, we can use Portable Class Libraries (PCLs).
How Xamarin Works on Android
Android Build + Execution Model
Xamarin.Android takes advantage of Just In Time (JIT) compilation on the Android device.
Android Build + Execution Model
• MCW – managed callable wrappers,
mostly managed by Mono.Android.dll
• ACW – Android callable wrappers
Always Up-to-DateXamarin.iOS offered same-day support for :
iOS 5 / iOS 6 / iOS 7 / iOS 7.1 / iOS 8 / iOS 9
Xamarin offers full support for: • Google Glass• Android Wear• Amazon Fire TV • Apple Watch and more
Development Environments
Visual Studio 201X
Xamarin Studio (PC + Mac)
Code Sharing Techniques
Code Sharing Techniques
There are multiple ways in which you can share code:• portable class libraries (PCLs)• partial classes• compiler conditional blocks• shared projects
Xamarin Architecture Guide
Xamarin Architecture Guide
Demo Time
What is MVVM?
MVVM vs MVC
In the MVVM the logic is stored in the presenter and the view is completely isolated from the model.
Model View ViewModel
MVVM Technical DetailsIt is derived from the Model View Controller Pattern.
• properties• data binding• INotifyPropertyChanged• INotifyCollectionChanged• IValueConverter• ICommand• UI thread
Why MVVM?
MVVM Pros and ConsThere is a reason why it’s called a pattern.Pros:• separation of concerns• decoupling• code reuse• testability
Cons:• MVVM is "overkill" for simple UI operations
The MvvmCross Magic
The MvvmCross Magic
It’s an open-source framework maintained by Stuart Lodge & Co.
It has Dependency Injection built-in -> Interface Driven Design.
It has a lot of plugins already written such as location, emails, gallery, network, SQLite, secure storage, phone calls etc.
#IF plugins -> less work for the developer, but also less control.
The MvvmCross Magic
The MvvmCross Magic
MvvmCross has support for:• Xamarin.iOS• Mac• Xamarin.Android• Windows Presentation Foundation• Windows Phone• Windows 8• Universal Windows Platform
The MvvmCross MagicIt has huge popularity and the community is very active.
https://jabbr.net/#/rooms/mvvmcrosshttps://xamarinchat.slack.com/messages/mvvmcross/https://github.com/MvvmCross/MvvmCross
Data Binding, Commands, Navigation
Data Binding - Properties
No C#, just XAML
<TextBox Text="{Binding Password, Mode=TwoWay}" />
Data Binding - Properties
No C#, just XML
xmlns:local="http://schemas.android.com/apk/res-auto"<EditText local:MvxBind="Text Password"
Data Binding - Properties
Just C#
var set = this.CreateBindingSet<LoginViewController, LoginViewModel>(); set.Bind(textField_Password).To(vm => vm.Password);
Data Binding - ListviewsNo C#, just XAML
<ListBox ItemsSource="{Binding MyCollection}"<ListBox.ItemTemplate>
<DataTemplate> …..</DataTemplate>
</ListBox.ItemTemplate></ListBox>
Data Binding - Listviews
No C#, just XML
<Mvx.MvxListView local:MvxBind="ItemsSource MyCollection; ItemClick ViewDetailsCommand"local:MvxItemTemplate="@layout/item_template_row" />
Data Binding - Listviews
Just C#
var set = this.CreateBindingSet<XViewController, XViewModel>();set.Bind(source).To(x => x.MyCollection);set.Apply();
ViewModel Commands
No C#, just XAML
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"xmlns:commandbinding="clr-namespace:Cirrious.MvvmCross.WindowsPhone.Commands;assembly=Cirrious.MvvmCross.WindowsPhone" <TextBlock Text="{Binding Name}">
<i:Interaction.Triggers><i:EventTrigger EventName="Tap">
<commandbinding:MvxEventToCommand Command="{Binding MyCommand}" />
</i:EventTrigger></i:Interaction.Triggers>
</TextBlock>
ViewModel Commands
No C#, just XML
xmlns:local="http://schemas.android.com/apk/res-auto"<Button local:MvxBind="Click LoginCommand" />
ViewModel Commands
Just C#
var set = this.CreateBindingSet<LoginViewController, LoginViewModel>();set.Bind(btn_Login).To(x => x.LoginCommand);set.Apply();
Navigation
Go forward:CurrentViewModelInstance.ShowViewModel<NewViewModel>();
Navigation
Go back:CurrentViewModelInstance.Close(this);
MvvmCross App Architecture
App ArchitectureThe project should be split in 2:
Common core which contains:• models• viewmodels• business logic• data access layer
UI-project per platform:• each platform views
Small Demo Time
MvvmCross Pros & Cons
Pros:• interchangeable code module• supports Test Driven Development (TDD)• it follows the Core pattern• it has data binding
MvvmCross Pros & Cons
Cons:• it is a non-native pattern for iOS -MVC- and Android -
aprox MVC-• core 3rd party dependency• lot’s of glue code for custom bindings
Xamarin Pros & Cons
Pros:• native experience• you can use a lot of components that .NET developers
already use• shared code base• only one programming language
Xamarin Pros & Cons
Cons:• you need a Mac• it has a license fee per developer, per platform -> $• bugs can appear: https://bugzilla.xamarin.com/• C# is needed
Xamarin Pros
Thank you very much!