Architecture of a watchOS app

At this point, we've explored what an Apple Watch app is composed of, how it differs from iOS, and how it should function. Now it's time to take a look at how we actually write a watchOS app.

Before you get too worried, most of what we've learned so far will carry over to watchOS. We're still using Xcode, we're still using storyboards, and we're still using Swift. However, since battery life is a much bigger concern on watchOS, there are some pieces of the process that work a bit differently in order to keep the amount of actual processing time to a minimum. We're also working with considerably less performance than we are used to on iOS, so there is also going to be a bit more magic going on to ensure smooth operation—there isn't a lot of room for complex animations and the like.

Target bundles

First, let's talk about the different target bundles that are part of the Apple Watch target. Earlier in the book, we touched on what targets are, but as a quick recap...