With Apple Watch OS update, apps are about to get a whole lot more capable

The changes come with watchOS 2, an update that's due in the Fall and will also bring new watch faces and other advances to end users. For developers, the highlight is that their apps will be able to make use of Apple Watch hardware features like the digital crown, accelerometer and heart rate sensor.

People who use the personal training app BodBot, for example, won't have to enter as much workout information manually now that the app can gather data from the watch's sensors, said Sergio Prado, who co-developed the program.

That's because the app will be able to use the watch's accelerometer to determine when people are lying on a weight bench, for instance, and then track how many repetitions they complete.

Having sensor access will also allow for a more personalized workout. Being able to hook into the heart sensor will allow the app to determine if a person is working out too hard and suggest a rest period. If that rest period is too lengthy, Prado said, the BodBot app could use the watch's taptic engine to give a tap to the wrist, indicating that it's time to resume working out.

WatchOS 2, available to developers now in beta, also brings video playback to the Apple Watch. Don't expect the device to handle lengthy clips though. Prado suspects Apple will issue development guidelines that restrict file sizes or limit videos to short clips.

Apple also shared that third-party apps will be able to connect directly to Wi-Fi networks, allowing programs that need a Web connection to work even when the Watch isn't connected to an iPhone via Bluetooth. That means people using a fitness app at the gym won't need to carry their iPhone around for the app to work properly.

Developers have been clamoring for access to the watch's hardware since it went on sale in April. Not being able to use the digital crown and sensors meant developers were essentially writing apps for a less powerful iPhone, instead of programs that use the watch's unique components, said Maximo Cavazzani, CEO of Etermax, which makes the game Trivia Crack.

That's all changed now, as Apple explained at its Worldwide Developers Conference Monday.

Giving outside developers similar capabilities as Apple's own software engineers was a logical step, and a necessary one to let them build apps that will keep the Apple Watch competitive with its rivals, Cavazzani said.

Access to those hardware features can lead to "big changes in how you use the app," he said.

Developers will be able to add features that they haven't yet been able to consider, said Hamid Palo, mobile lead at Trello, which develops a Web-based project management app of the same name. He could see developers creating a watch app that uses HomeKit, Apple's smart home platform, to turn on the lights in a room as people walk around their house.

By letting the Apple Watch handle app logic instead of depending on the iPhone, people will see apps responding to commands more quickly, said Palo.

Right now, information is exchanged between the watch and iPhone via Bluetooth, an experience that results in some apps loading slowly. Letting apps run natively on the watch will eliminate the need to communicate with an iPhone, shaving as much as two seconds off the time it takes to complete a transaction, Palo said.

Assuming Apple Watch apps are designed for transactions that take 10 seconds, that's a 20 percent difference, which in app terms is huge, he said,

"More people will use watch apps because the experience will be that much better," Palo said.

Fred O'Connor writes about IT careers and health IT for The IDG News Service. Follow Fred on Twitter at @fredjoconnor. Fred's e-mail address is fred_o'connor@idg.com