The company told developers they could make a couple kinds of actions occur on the watch, mostly notifications appearing from a linked iPhone, much like the many Android-based smartwatches.

But there was one important catch: The actual processing power for this first generation of apps has to come from a linked iPhone. Only the user interface would appear on the watch. Such an app wouldn’t work at all if the owner didn’t also have their iPhone close at hand. Apple said

Putting all the computing action on the phone should prevent app developers from doing anything that will overtax the Apple watch processor or deplete the battery too quickly. But it also allows developers to get a head start on designing unique and useful watch apps now, instead of forcing them to wait another year.

Apple is also trying to make developers keep it simple. If you’ve tried any of the Android smartwatches, the apps can get a little confusing, with clicks and taps and swipes. Apple told developers that their apps should stick to a single style of navigation, either a hierarchy that users click deeper into or a series of pages that users swipe through.

Apple is also trying to make developers keep it simple. If you’ve tried any of the Android smartwatches, the apps can get a little confusing, with clicks and taps and swipes. Apple told developers that their apps should stick to a single style of navigation, either a hierarchy that users click deeper into or a series of pages that users swipe through.