I’m all for it. I think Apple has shown that customisation and individual personality are major selling points of the Apple Watch for customers. In the Apple Watch’s debut keynote, Tim Cook said as much: “it’s incredibly customisable, so you can find one that reflects your personal style and taste”. In the hardware, you have thousands of chassis material and band combinations to choose from. watchOS has a surprisingly plentiful number of interface options, with different modes for Dock, alternative Home Screen layouts, and countless complications and appearance styles for the faces themselves. A third-party Watch clock face store is the next big frontier in this space.
Opening up the primary interface of the Watch fits the themes of the platform. Whereas the lock screen and home screen of iOS remain uniform and locked down, with basically no user customisation opportunities beyond setting a wallpaper, watchOS has forged a different path. It makes sense that wearable devices are more adaptable. They are more personal.
What’s really fascinating about this rumour from a technical perspective is how will third-party faces be developed. What is the toolkit? The WatchKit frameworks are far too limited to support the rich, diverse, and dynamic interactions that a good Watch face would require. WatchKit is just not suited for making a clock face, at all. The introduction of a clock face SDK has to come with a new UI framework for watchOS. Something that is far closer to UIKit in freedom and flexibility. And — fingers crossed — this would be available for developers to use in Watch apps as well as clock faces.
As optimistic as I am, approach code references like this with some hesitation. A log message in a codebase does not necessarily indicate an imminent later-this-year release. This could be an engineer simply thinking ahead for plans that might not play out for a few more major releases. It doesn’t confirm that third-party clock faces are coming with watchOS 5. It does heavily imply that they are on the roadmap, somewhere on the list of todos, and Apple is serious enough about it that engineers are already thinking about how to make it work.