To some extent, users are, by complementing an iPhone with an Apple Watch, extending the reach of the device they already know, and widening the range of ways they have to interact with much of the software they already use. Indeed, at the time of writing, Apple does not accept submissions of apps that provide functionality exclusively for the Watch, demonstrating quite clearly their current view of how the Watch fits into the ecosystem. In this model, the watch is very much an extra level of engagement with the phone, and introduces what may well become a dominant feature of wearables development, namely that the physical separation of two devices does not need to be a fundamental part of the relationship between them. In a sense, it is like taking a small bit of screen and a button or two from the watch, and locating it somewhere more convenient, for use in appropriate situations. Apple's emphasis on fitness tracking is a great example, but should be viewed more as some smart reading of the nascent market for wrist-borne computers, than as an indication of some imagined limit on the scope of the Watch's utility. These are very early days, and it would be a foolhardy author who risks a prediction of the ways in which our use of wearables will evolve in the next few years, that is still very much in the stars. But evolve it will, of that we can be sure.
And it is because of this wide open scope for development and yet-to-be-discovered potential that we also need to be able to view the Apple Watch as not simply an extension of the iPhone (though it certainly is that), but also as an autonomous device in its own right, one that can collect data from a number of sources (whether the user, the phone or the web), process that data natively, present it visually or otherwise, at its own initiative, and even store that data onboard or online. Since the release of watchOS 2, the limitations of what we can do independently of the phone are defined more by our imagination than by actual barriers inherent in the technology, and the Watch fits in perfectly with the tendency of apps to be increasingly spread across devices and platforms. Most users of social networks, for example, will regularly use more than one platform to catch up on what's going on and update their status, typically a web browser on a laptop and a phone app, but this trend is being broadened across a whole range of software categories, as users increasingly expect to be able to use apps across several devices according to whatever is appropriate to their situation.
And so we have an operating system, watchOS, that is both a part of its larger sibling, iOS, and a separate OS in its own right, that perfectly mirrors the relationship between the physical watch, and its larger counterpart in our pockets. The relationship between WatchKit and UIKit is the same. Our success in designing and developing for this platform will likely depend to a significant extent on our ability to embrace this dual personality.
If that sounds like an exciting challenge, and a stimulating environment in which to expand your skills as a developer, then this book is for you.