The Apple Watch team does a tremendous amount of testing on watch code. It’s unacceptable to glance at your watch and find the face has frozen, crashed, or has a visible glitch. It must be as utterly bug-free as possible.
The watchOS code that drives the watch face runs 24 hours a day, for months on end. If Apple were to open up watch-face development to third-party developers right now, battery life would almost certainly decline, which would make for a worse Apple Watch experience for users. No matter how capable or diligent they might be, third-party developers simply won’t have the internal graphics knowledge, the private API access, or the test tools to be as rigorous about battery life as Apple demands. Battery life is an obsession with the Apple Watch team. If battery life goes down, engineers are assigned to find out why and to fix it. The results are published to an internal Web dashboard that tracks battery life for every watchOS build. They run through a set of scripts that simulate normal use to see how long the batteries last. The daily build is also loaded onto a rack of Apple Watches in the power testing lab.
(This is true for all Apple operating systems see “ How to Decode Apple Version and Build Numbers,” 8 July 2020.) Apple engineers use the daily build, so they’re all running the latest version of watchOS. Every night, Apple’s automated build system creates a new build of watchOS, called the daily build, using the latest code changes checked into source control. Apple engineers spend thousands of hours fine-tuning the code to be power-efficient. The Apple Watch doesn’t achieve all-day battery life by accident. And they have internal testing and measurement tools that the company doesn’t provide to third-party developers. They have access to private graphics APIs that aren’t available to third-party developers. Their animation techniques are the most energy-efficient possible. They know which graphics techniques use the least power. Apple engineers have intimate knowledge of how watchOS displays graphics and how the Apple Watch’s GPU works, and for better or worse, this information is proprietary. These efforts go well beyond simple tricks like hiding the second hand when the face dims since animation takes more power than a static display. Apple engineers go to great lengths to ensure the watch face code is power-efficient. It’s vital that the code driving the watch face consumes as little power as possible. On the Apple Watch Series 5 and Series 6, the watch face is displayed almost all the time. The main reason Apple doesn’t allow third-party watch faces is battery life. While I don’t have any inside information about current versions of watchOS and Apple Watch hardware, there are at least four reasons to think Apple won’t support third-party watch faces any time soon, if ever.
But despite the pleas of users, developers, and a well-known podcaster, they’re probably not coming.Īs an Apple software engineer, I worked on the first two releases of watchOS, so I’m familiar with many of the Apple Watch’s internal trade-offs. smart displays, iOS 12.5.5 and Catalina security update, iPhone 13 problem with Apple Watch unlockingįour Reasons Why We Won’t See Third-Party Apple Watch Faces (And What Apple Is Doing Instead)Īpple Watch users have wanted third-party watch faces since Apple unveiled the watch in 2015, and developers have wanted to create custom watch faces for just as long. #1581: New Safari 15 features, Center Stage vs.#1582: iOS 15.0.1 and iPadOS 15.0.1, Apple Watch Series 7 dates, cautionary tale about backups, using Live Text and Safari extensions.#1583: Ten years without Steve Jobs, iOS 15.0.2, Exif and Visual Lookup in Photos, iPadOS 15 multitasking, easier 2FA codes.#1584: New MacBook Pros, new AirPods and HomePod mini colors, Monterey release date, notification grouping tip, Find My story.