The Digital Crown is the primary hardware input for Apple Watch. As people rotate the Digital Crown, it generates information you can use to enhance or facilitate interactions with your app, like scrolling or operating standard or custom controls. However, your app can't respond when people tap the Digital Crown, because watchOS reserves these tap interactions for system navigation. For developer guidance, see WKCrownDelegate.
Apple Watch Series 4 and later provides haptic feedback for the Digital Crown, which gives people a more tactile experience as they scroll through content. By default, the system provides linear haptic detents — or taps — as people rotate the Digital Crown. Some system controls, like table views, provide detents as new items scroll onto the screen.
Provide visual feedback in response to Digital Crown interactions. For example, pickers change the currently displayed value as people use the Digital Crown. If you track rotations directly, use the rotational data you receive to update your interface programmatically. If you don’t provide visual feedback, people are likely to assume that rotating the Digital Crown has no effect in your app.
Update your interface at a rate that corresponds to the Digital Crown rotation. Rotations of the Digital Crown should give people precise control over an interface. Consider using the rotational velocity to determine the speed at which you make changes. Avoid updating content at a rate that makes it difficult for people to select values.
Use the default haptic feedback when it makes sense in your app. If haptic feedback doesn't feel right in 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 them use linear detents instead of row-based detents. For example, if your table has rows with significantly different heights, linear detents may give people a better experience.