Short review of APPLE's HIGs https://developer.apple.com/library/prerelease/ios/documentation/UserExperience/Conceptual/WatchHumanInterfaceGuidelines/index.html#//apple_ref/doc/uid/TP40014992-CH3-SW1

1. WATCH short HIG

2. App anatomy Basics
Hierarchical
Page-based

3. Glances Basics
Template-based
Not scrollable
Associated with a single action
Optional.

4. Notifications Basics
Short notifications

5. DetailsLong notifications
Notifications Basics

6. Modal sheets Basics

7. Layout Basics
Limit the number of side-by-side controls in your interface.
Use the full width of the screen.
Apps use relative positioning for items.
Prefer the use of left alignment during layout.
Make text buttons full width.
Use the context menu to present
secondary actions.
Provide image assets for different
screen sizes as needed.

8. Color and Typography Basics
Use black for your app’s background color.
Use your app’s key color for branding or status.
Use high contrast colors for text.
Avoid using color as the only way to show interactivity.
Be aware of color blindness.
Color communicates, but not always in the way you intend.
Use the built-in text styles whenever possible.
Prefer the use of a single font throughout your app.
When specifying system font sizes manually, the point size
determines the correct size to use.

9. UI Elements
Labels
Displays any amount of static text
Does not allow direct user interaction
Can be updated programmatically
Can span multiple lines
Image
Has no appearance of its own; it only displays its image
Does not support user interactivity
Provides programmatic controls for starting and stopping animations

10. Groups
Can lay out items horizontally or vertically
Contains one or more other interface elements
Has attributes for specifying margins and spacing among group elements
Can display an image or solid color as a background
Has a configurable corner radius for its background and content
Tables
Supports multiple row types
Is scrollable
Can have a background color or image
UI Elements

11. Buttons
Has a background that can be customized
Has rounded corners
Can contain a label or group object
Switches
Indicates the binary state of an item
Always includes a label
UI Elements

12. Maps
Configure the map region to be the smallest area that encompasses the relevant
locations.
Do not create a map object whose size exceeds the size of the available content area.
Use annotations to highlight locations on the map.
Sliders
Consists of a horizontal track with images at either end for manipulating the slider value
Can display the current value as a set of discrete steps or as a continuous bar
Always increments and decrements its value by a predetermined amount
Does not display its numerical value to the user
UI Elements

13. Dates and Timers
Displays the date, time, or a combination of the two
Can be configured to display the date and time using a variety of formats, calendars,
and time zones
Does not need to be updated by your WatchKit extension
Menus
Menus display between one and four actions.
Menu actions apply to the current screen.
Each action must have an image and a label string.
Menus are optional.
UI Elements

14. Icon and Image Sizes
Asset Apple Watch (38mm) Apple Watch (42mm)
Notification center icon
Home screen icon
Long look notification icon
Short Look icon
48px
80px
172px
55px
88px
196px

15. Menu Images
Device Canvas size Content size
Apple Watch (38mm)
Apple Watch (42mm)
70px
80px
46px
54px