The Digital Crown lets users scroll content without obstructing their view of that content, but you can also use Digital Crown input to create sophisticated custom interfaces. Apps can either directly access the Digital Crown, or indirectly access the crown through system controls like pickers. With direct access, your app receives the raw rotational data and it is up to you to decide how best to use that data. Use pickers to display a navigable list of items and handle the selection of an item from that list.
Provide visual feedback in response to Digital Crown interactions. Pickers provide feedback by changing the currently displayed value. When tracking rotations directly, use the rotational data you receive to update your interface programmatically. If your app does not provide visual feedback, the user will assume that rotating the Digital Crown has no effect.
Update your interface at an appropriate rate. Rotations of the Digital Crown should give the user precise control over changes to your interface. Consider using the rotational velocity to determine the speed at which you make changes. Avoid updating content too quickly or slowly if doing so makes it difficult to select values.
Apple Watch Series 4 provides haptic feedback for the Digital Crown, creating a more tactile experience as the user scrolls through content. By default the system provides linear haptic detents—or taps—as the user rotates the crown. Some system controls, like table views, provide detents as new items scroll onto the screen.
Use the default haptic feedback. If haptic feedback doesn't feel right within the context of your app—for example, if the linear detents don’t match your app’s animation—disable the detents. You can also adjust the haptic feedback behavior for tables, letting the table use linear detents instead of the row-based detents. For example, if your table has rows with significantly different heights, linear detents may produce a better feel.