I got simple iOS app for tracking flight status. I want create extension for Apple Watch. But I don't want create any interface. Just sending notifications to user if flight status changes.
Have you got idea how to do it? Maybe someone know good tutorials for that?
You can use a "Glance" just to send a quick update like that, but you need to create the Glance UI separately anyway, and it's part of the same Watch App package.
Interacting w/a Glance is also supposed to open the Watch app and allow the user to view the info in greater detail/context. Not sure if you can have it just do nothing - that'd likely just appear to be broken/unresponsive, which you probably don't want.
Ray Wenderlich has several tutorials and an entire book on WatchKit. This link is Part 3 of a series on WatchKit apps that includes using Glances in a similar way: http://www.raywenderlich.com/96741/watchkit-tutorial-with-swift-tables-glances-and-handoff
Edit: As stated by @bgilham, if you don't want to customize the interface, you can send a notification that will use a stock UI on the Watch. A "Short Look" is a single screen w/limited space & no actions. A "Long Look" can scroll & contain action buttons. See the Apple Watch Programming Guide on Notifications for details.