To cope with Apple Watch's relatively small screen size, Apple introduced a hardware feature called Force Touch that invokes app and UI commands with a firm press of the screen. Being hidden by design, these contextual menu options provide deep app control without cluttering the watch face, but can easily be overlooked.
Unlike iOS and OS X user interface input tools, Force Touch-based interactions are not accompanied by visual cues like icons and cursors. Without reading the Apple Watch users guide, it takes a bit of experimentation to discover and master these menus as their functions change from app to app.
Starting with Messages, seen above, a firm press down on the main conversations overview lets users quickly create a new chat. Selecting the New Message icon brings up a pane with two text fields, one for contact selection and another for entering text into the message body.
Users can choose from recent contacts, anyone in their Contacts list or opt to dictate a telephone number. Dictation is also used for entering in message text.
The Music app features a deeper set of commands and access to system settings colocated in Watch's Settings app. A firm press from the main screen brings up options to change sources, for example between iPhone and onboard data, as well as a shortcut to the Now Playing pane. These same choices are available across the app.
The Now Playing pane's Force Touch menu includes commands for shuffling and repeating tracks, changing sources and outputting audio to connected AirPlay devices.
Calendar's Force Touch implementation is less involved with a total of three menu options. The commands are useful, however, as they determine how events are presented in-app. Users can choose from a plain list view or a day view that mirrors a timeline as seen on iOS.
As a final example, performing a Force Touch operation in Stopwatch calls up display options, while the same procedure in Timer lets users switch between 12-hour and 24-hour watch faces. The latter is not merely for aesthetics, as selecting the 24-hour face extends Timer functionality by 12 hours.
Most of Apple's first-party apps include some form of Force Touch integration, as does the Apple Watch UI. Notifications can be cleared, alerts customized, settings changed and more. Third-party app makers are taking the protocol even further by mapping commands integral to app functionality. For example, Calcbot requires a firm press to access calculator function buttons.
As with any new technology, the more you experiment with Force Touch, the more you become familiar with firm presses and the contextual menus they provide. With Apple Watch, the learning process is part of the fun.