Developing Apps With WatchKit A Whirlwind Tour Adam Shaw Kabuki - - PowerPoint PPT Presentation

Developing Apps With WatchKit

Adam Shaw

Kabuki Vision

A Whirlwind Tour

@KabukiVision

Dressed NoteMaster Journaling

WatchKit

• SDK for building apps for Apple Watch
• Similar, but different from iOS app development
• Very limited
• Can’t build true “native” apps
• Need
• Xcode (Mac)
• Apple Watch
• iPhone

WatchKit Extensions

WatchKit app is an extension to an iPhone app. “Starting later next year, developers will be able to create fully native apps for Apple Watch.”

— Apple, Nov 2014

WatchKit Extensions

• WatchKit App


• Glance (optional)


• Notification (optional)

Architecture

WatchKit App

Storyboard Resources

WatchKit Extension

Code! Resources

iPhone App

Code Resources

WatchKit WatchKit

Architecture

WatchKit Extension

Code Resources

WatchKit

iPhone App

Code Resources

Shared Data

Limited Communication

Architecture

• WatchKit app distributed as part of iOS app
• WatchKit code in “WatchKit extension”
• None of your code runs on the watch!
• All of your WatchKit extension code runs on

iPhone (in separate background process from main app)

Things you CANNOT do

Hardware sensors (heart rate, step counter, accelerometer, etc)

Things you CANNOT do

Wireless Communications

Things you CANNOT do

Core Animation CAN animate as sequence of images (like an animated GIF)

Things you CANNOT do

Multi-touch gestures Swiping, dragging, etc.

Things you CANNOT do

Direct access to speaker or microphone

What CAN you do?

• Basically:
• Put stuff on the screen
• Respond to simple button taps
• Use iPhone features (GPS, networking, etc.)
• Change stuff on the screen

UI created using storyboards in Xcode’s Interface Builder

User Interface

Storyboards

User Interface

Interface Elements

• Text labels, buttons, images
• Switches, sliders, separators,

maps

• “Text” input (via voice)
• Groups
• Tables

• Everything must be defined in the storyboard
• No dynamic creation of interface elements in code

(mostly)

• Most attributes (color, image, text, etc) can be controlled

in code

• “Hidden” attribute can be used to effectively add/remove

elements from the interface

• Table “rows” are the only elements that can be

dynamically added/removed in code

User Interface

Interface Elements

• All layout defined in storyboards
• No auto layout, no explicit positioning
• Relative positioning - interface objects laid out

vertically or horizontally

• Content expands downward, allowing vertical

scrolling

• Two different watch sizes

User Interface

Interface Layout

User Interface

Interface Navigation

Hierarchical Page-based Modal Can’t mix and match hierarchical and page-based (at the same level)

User Interface

Images

WatchKit App

Installed Images

WatchKit Extension

Code! Cached Images

Sharing Data

WatchKit extension & iOS app

WatchKit Extension

Sandbox

iPhone App

Shared Data

Sandbox App Group XYZ App Group XYZ

Communication

WatchKit extension & iOS app

WatchKit Extension

Sandbox

iPhone App

Sandbox

• penParentApplication:reply

application:handleWatchKitExtensionRequest:reply:

Communication

WatchKit extension & iOS app

WatchKit Extension

Sandbox

iPhone App

Sandbox

Darwin Notifications (MMWormhole)

Networking

WatchKit Extension

Sandbox

iPhone App

Sandbox

• penParentApplication:reply

application:handleWatchKitExtensionRequest:reply:

???

Shared Data

Gotchas

• Unpredictable and merciless lifecycle
• WatchKit extension can and will be killed at

any time without warning

• User puts down wrist
• Screen timeout

Gotchas

• UI Performance
• Communication speed and latency between

iPhone and Apple Watch

• Dynamically generated images sent over to

watch from iPhone

• Watch not fast at loading images, period
• Reacting to button taps are a two-way trip

Gotchas

• Permissions (contacts, images,

location etc.)

• Only main iOS app can trigger

these

THANKS!

Adam Shaw

Kabuki Vision

@KabukiVision

Dressed NoteMaster Journaling