Apple Watch ‘apps’ are really extensions to iPhone apps. Don’t try to recreate functionality more suited to a performing on a larger device (eg: typing). Apple Watch extensions should augment iPhone apps by allowing the wearer to interact with important information in a convenient, non-obtrusive way. The user should not have to lift their arm any longer than 5 seconds to view the watch. Use handoffs to the app running on the phone when the app requires longer, or more detailed user input.