Pressing firmly on the Apple Watch display causes the current screen’s menu (if any) to appear. A menu can display up to four relevant actions for the current screen without taking away space from your interface.
Include a menu when the current screen has relevant actions. Menus are optional. If no menu is present, the system plays an animation when the user presses firmly on the display.
Use a label and an icon to convey the purpose of each menu action. Both the label and the icon are required. Labels are limited to two lines, so the text should be short. To learn about designing menu icons, see Menu Icons.
Use menus for their intended purpose. Menus are a way to access actions that modify the contents of the current interface controller. Never use them as the primary form of navigation in your app.
Avoid replicating the visual style of menus in other parts of your app. If you must use a similar layout, apply color to your interface or arrange items in a way that differentiates them from menus.
For developer guidance, see WKInterfaceController.