One of the biggest problems with third-party apps on the Apple Watch is that they don't run natively and can't gather data directly from the Watch's own sensors. This makes them more sluggish and feature restricted to Apple's own apps--they simply can't keep up.
But Apple will soon open up more possibilities for Apple Watch development, according to Jeff Williams, Apple's operations chief and the executive in charge of the Apple Watch. On Wednesday, Williams told Walt Mossberg at the Code Conference that developers would get an Apple Watch SDK at this year's Worldwide Developers Conference, which kicks off Monday June 8 in San Francisco.
Fitness apps are a natural fit for the Apple Watch, since it has an accelerometer and heart rate sensor that work even when the Watch isn't paired with an iPhone. And that makes them a perfect example for how the Watch experience will improve when these apps can go native and collect data directly from the onboard sensors.
Right now, the Watch's sensors can collect data and send it to the Health app on your iPhone. You can then choose to share that data with HealthKit-compatible apps on your iPhone, which can then report back to their Apple Watch counterparts. The third-party apps you see on your Apple Watch are really just displaying information on behalf of the related iPhone app--no computing tasks are happening on the Watch itself.
By contrast, a fitness app running natively on the Apple Watch could provide better information and faster performance. A running app could give you near-real-time coaching based on your heart rate and how many strides you're taking per minute, for example, even if you didn't bring your iPhone along. Williams cited the popular cycling app Strava as another that could really benefit from access to the Watch's sensors.
Williams said developers would get the new SDK at the developers conference, and be able to launch their apps in the fall. He wouldn't give a firm idea of how many Apple Watch units the company has sold, but assured Mossberg that the demand divided by the supply is greater than one. That means they can't make them fast enough, and indeed, we know plenty of people who ordered day one who still haven't received theirs.