Inside the event, Apple advertised its operating systems for its iPhone, Mac and Watch but gave no other indication of the announcements to come.
But at a recent tech event, a top Apple executive said the tech giant's legion of independent developers will get a preview of a new software kit for the two-month-old Apple Watch at the conference. Apps built with the new toolkit will likely start arriving in the fall, said Jeff Williams, Apple's senior vice president of operations.
Like other Apple products, the watch's commercial success will likely hinge on a compelling collection of apps. But early apps for the timepiece have been tethered to the iPhone, placing some limits on what developers could do.
The expanded software kit should lead to better and faster watch apps, said Bob O'Donnell, an analyst at TECHnalysis Research.
Many analysts expect that Apple will use the event to debut a new music streaming service, and in an interview in Cannes, France, the CEO of Sony Music, Doug Morris, confirmed the launch although he did not provide many details, according to a report in VentureBeat.

The company behind the iPod and iTunes has long been a leader in digital music, but it has lost ground in recent years as subscription services such as Spotify have caught on with consumers.
Analyst Van Baker of Gartner said he expects Apple to release a new service to win a bigger share of the streaming business.