While Apple got off to a slow start on hiring for machine learning jobs, it is closing in on its competitors, said Oren Etzioni, who is CEO of the Allen Institute for Artificial Intelligence and a professor at the University of Washington.
"In the past, Apple has not been at the vanguard of machine learning and cutting edge artificial intelligence work, but that is rapidly changing," he said. "They are after the best and the brightest, just like everybody else."
Acquisitions of startups such as podcasting app Swell, social media analytics firm Topsy and personal assistant app Cue have also expanded Apple's pool of experts in the field.
Apple does not reveal the number of people working on its machine learning efforts.
But one former Apple employee in the area, who asked not to be named to protect professional relationships, estimated the number of machine learning experts had tripled or quadrupled in the past few years.
Many of the currently posted positions are slated for software efforts, from building on Siri's smarts to the burgeoning search features in iOS. The company is also hiring machine learning experts for divisions such as product marketing and retail, suggesting a broad-based effort to capitalize on data.
Apple's hiring mirrors a larger hunt in Silicon Valley for people who can help companies make sense of their huge stashes of data, said Ali Behnam, managing partner of Riviera Partners, an executive search firm. Data scientists are the most sought-after experts in the market, he noted.
Asked for comment about Apple's strategy, a company spokeswoman pointed to statements from Craig Federighi, senior vice president of Software Engineering, who described the release at a developers' conference in June as "adding intelligence throughout the user experience in a way that enhances how you use your device but without compromising your privacy, things like improving the apps that you use most."
But Google and others have an edge in spotting larger trends, meaning Apple's predictions may not be as good, said Gonzalez, echoing a commonly held view among machine learning experts.
What's more, there are some features for which Apple has yet to find an answer, such as Now on Tap, which Google will release this fall. When users press the home button, Google will scan their screens to deliver helpful information—a user reading about an upcoming movie, for example, might receive reviews or a list of showtimes. It would be difficult to deliver such services without sending data to the cloud, experts say.