Creating Apple Watch Experiences with C# and Xamarin

1. CREATING APPLE
WATCH EXPERIENCES
WITH WATCHKIT AND XAMARIN
ED SNIDER
@edsnider
NORTHERN VA MOBILE C# DEV GROUP – APRIL 8, 2015

2. INTRO
I AM ED SNIDER
Senior Developer at InfernoRed Technology
Organizer of Northern VA Mobile C# Developers Group
Xamarin MVP
@edsnider
www.edsnider.net

3. AGENDA
• Setup requirements
• The Apple Watch model
• WatchKit apps
• Architecture
• Lifecycle
• Design
• Navigation
• Parent app
• Glances
• Notifications
• Apple Watch and WatchKit limitations

4. SETUP REQUIREMENTS
• OSX Mavericks or Yosemite
• Xcode 6.2
• iOS 8.2 Simulators
• Xamarin.iOS 8.8
• Xamarin Studio 5.8 and/or Xamarin for Visual Studio 3.9
• Complete setup and installation instructions available at:
http://developer.xamarin.com/guides/ios/watch/installation/

5. THE APPLE WATCH MODEL
Core Components of an Apple Watch app:
Parent / Containing iPhone App
WatchKit Extension
WatchKit App
Glance
Notifications
Apple Watch apps are bundled with (and require) an iPhone app – no 3rd party stand

6. WATCHKIT APP ARCHITECTURE
WatchKit app
• Lives on the Watch
• Contains UI elements only
WatchKit
app
WatchKit
extension
WatchKit app
+
WatchKit
extension
WatchKit extension
• Lives on the iPhone
• Controls app interface
• Contains app logic
• Communicates with parent app
Parent iPhone
app

7. WATCHKIT APP ARCHITECTURE :
INTERFACE OBJECTS
Watch app interfaces are manipulated and controlled via interface
objects in the WatchKit extension controllers (WKInterfaceController)
Interface objects provide a proxy between the WatchKit extension
and the actual views (aka controls) in the Apple Watch app
Setters only – you cannot get a view’s (aka control’s) attribute
values at runtime
Automatically created (in *InterfaceController.designer.cs) based on
the storyboard outlets and actions

8. WATCHKIT APP ARCHITECTURE : APP
LIFECYCLE
Awake(NSObject context)
4. WKInterfaceController Lifecycle
WillActivate()
1. Launch App
2. Load scene from Storyboard
3. Create WKInterfaceController

9. WATCHKIT APP DESIGN : USER EXPERIENCE
Controls:
• Label, Button, Switch, Slider, Separator, Image, Map
• prefixed with WKInterface
Layout:
• Group
• Table – similar to a ListView; provides row selection handling (DidSelectRow())
Text Input:
• Pre-defined phrases
• Dictation
• Emoji

10. WATCHKIT APP DESIGN : SCREEN SIZES
136 x 170
pixels
156 x 195
pixels38mm 42mm

11. WATCHKIT APP DESIGN : CONTEXT MENUS
Each interface controller can have its own
context menu
Display up to 4 menu items (each with a title
and image)
Activated by user with “Force Touch”

12. WATCHKIT APP NAVIGATION
Page based navigation
• User navigates by swiping left
and right through a “carousel” of
pages
• Dot indicator shows current page
Hierarchical navigation
• User navigates by clicking
through pages
• Pages are pushed on and
popped off a navigation stack

13. WATCHKIT APP : WORKING WITH PARENT APP
• Use OpenParentApplication() to offload long running /
background tasks to the parent iPhone app
• Use app groups to share data between the WatchKit extension
and the parent iPhone

14. GLANCES
A Glance is part of the WatchKit app and WatchKit extension
The Glance’s interface is contained within the WatchKit app’s storyboard
and has its own special interface controller
Only one glance interface per WatchKit app
Same life cycle as WatchKit apps’ standard interface
Use timer to update the Glance’s interface and keep its data relevant

15. NOTIFICATIONS
Apple Watch displays notifications based on its parent iOS app’s
notification settings
By default, nothing is required to support notifications on Apple
Watch apps, including actionable notifications
Two interfaces - Short-look interface, then Long-look interface if the
user continues to look at it
Apple Watch notifications can be customized (long-look interface
only)

16. LIMITATIONS
• Watch apps require a parent iPhone app to be present
• Cannot dynamically add UI elements at runtime

17. RESOURCES
• XAMARIN WATCHKIT DOCUMENTATION:
http://developer.xamarin.com/guides/ios/watch/
• DEMO CODE: http://www.github.com/edsnider
Apple Watch frames: http://infinitapps.com/bezel/
iPhone frames: http://mockuphone.com/