Xamarin.Forms helps you build a native UI for three platforms with one shared C# codebase. Simply put, if you know C# then you already know how to build iOS, Android, and Windows apps. Leverage the .NET Framework to build out your shared business logic including integration with web services and Azure Mobile Apps and then build out your shared UI in C# or XAML. Xamarin.Forms also features a built-in two-way data binding, dependency service to help you implement platform-specific code, an advanced cross-platform animation system, support for custom controls, and lots of other powerful features to help you build the best apps possible in the least amount of time. This session will focus on the latest developments in Xamarin.Forms that will help you share more code and build more beautiful apps in less time. You will look at Custom Renders, Effects, Platform Specifics, Bindable Native Views, the Xamarin.Forms previewer, and more. You'll also look at tweaking and tuning your Xamarin.Forms applications for the best performance possible.

2. James
Montemagno
Principal Program Manager – Mobile Developer Tools,
Microsoft
motz@microsoft.com Montemagno.com @JamesMontemagno
Weekly development podcast
mergeconflict.fm
Weekly development show
xamarinshow.com

3. iOS C# UI Windows C# UIAndroid C# UI
Shared C# logic
Xamarin’s unique approach
Shared C# codebase • 100% native API access • High performance

4. Build native UIs for iOS, Android, and Windows
from a single, shared C# codebase.
Meet Xamarin.Forms

5. Xamarin + Xamarin.Forms
Traditional Xamarin approach With Xamarin.Forms:
More code-sharing, all native
iOS C# UI Windows C# UIAndroid C# UI
Shared C# Logic Shared C# Logic
Xamarin.Forms

6. What’s included
✓ 40+ Pages, layouts, and controls
(Build from code behind or XAML)
✓ Two-way data binding
✓ Navigation
✓ Animation API
✓ Dependency Service
✓ Messaging Center
Shared C# Logic
Shared UI Code

7. Pages
Stack Absolute Relative Grid ContentView ScrollView Frame
Content MasterDetail Navigation Tabbed Carousel
Layouts

8. ActivityIndicator BoxView Button DatePicker Editor
Entry Image Label ListView Map
OpenGLView Picker ProgressBar SearchBar Slider
Stepper TableView TimePicker WebView EntryCell
ImageCell SwitchCell TextCell ViewCell
Controls

9. Xamarin & Xamarin.Forms ecosystem

10. Native UI from shared code
<?xml version="1.0" encoding="UTF-8"?>
<TabbedPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MyApp.MainPage">
<TabbedPage.Children>
<ContentPage Title="Profile" Icon="Profile.png">
<StackLayout Spacing="20" Padding="20"
VerticalOptions="Center">
<Entry Placeholder="Username"
Text="{Binding Username}"/>
<Entry Placeholder="Password"
Text="{Binding Password}"
IsPassword="true"/>
<Button Text="Login" TextColor="White"
BackgroundColor="#77D065"
Command="{Binding LoginCommand}"/>
</StackLayout>
</ContentPage>
<ContentPage Title="Settings" Icon="Settings.png">
<!-- Settings -->
</ContentPage>
</TabbedPage.Children>
</TabbedPage>

13. Messaging Center
▪ Master Page:
▪ Detail Page:

15. XAML Compilation
XAMLCXAML
Parsed and inflated
Parsed & turned into IL

16. XAML Compilation Usage
At assembly level:
[XamlCompilation(XamlCompilationOptions.Compile)]
[XamlCompilation(XamlCompilationOptions.Skip)]
[assembly: XamlCompilation(XamlCompilationOptions.Compile)]
At class level:

18. • Image Loading & Caching
• Trimmed down just for Images
Introducing GlideX.Forms
http://jonathanpeppers.com/Blog/glidex-forms---fast-images-for-xamarin-forms-on-android

19. • Web Urls
• Files on disk
• Android resources (drawables)
• Byte array (
Install NuGet & Init

21. ListView CachingStrategy
✓ Improves scrolling performance
✓ RetainElement is currently the default

22. ListView CachingStrategy

23. Data Templates

24. Data Templates
ItemTemplate="{StaticResource WeatherTemplateSelector}"

27. • Extend Forms functionality
• Platform-specific
implementations
• Customize an existing
control or write your own
Custom Renderers

28. • Custom page (subclass PageRenderer)
• Circle Image (subclass ImageRenderer)
• Calendar (subclass ViewRenderer)
Custom Renderers - Examples

29. Effects
✓ Custom renderer “lite”
✓ Change properties on the native control
✓ Optional
✓ “stringly-typed”
X No methods or events
X No replacing the control

30. Effects

33. Shared C# Backend

34. iOS Large Titles
Platform Specifics
C#
XAML

35. Built-in UI Tweaks
Platform Specifics

36. Access Native Features Easily
Dependency Service

37. It is really fast!
Dependency Service
https://xamarinhelp.com/ioc-container-performance/

38. Shared C# Backend
User Interface User Interface User Interface
Geolocation Geolocation Geolocation
Compass Compass Compass
Keystore Keystore Keystore

39. SharedPreferences
Preferences.Get(“my_key”, 0);
NSUserDefaults ApplicationData

40. Xamarin.Essentials
Common API

44. ResourceDictionary
Improvements

59. Xamarin.Forms
Shared C# Logic
Windows C#Android C#iOS C#

67. https://github.com/praeclarum/Ooui

68. soundbite.fm

70. Thank you.
James
Montemagno
Principal Program Manager – Mobile Developer Tools,
Microsoft
motz@microsoft.com Montemagno.com @JamesMontemagno
Weekly development podcast
mergeconflict.fm
Weekly development show
xamarinshow.com