The revamp, unveiled at its annual Worldwide Developers Conference in Cupertino, California, introduces "Siri AI," a more conversational assistant with a standalone app and the ability to analyze what is on a user's screen and pull in information from the web. The update comes two years after Apple first promised major upgrades that were repeatedly delayed.

At its annual developers' conference, Apple put the spotlight on new AI features, while highlighting security and child safety — and critiquing the company's AI competitors.

Siri debuted in 2011 and is accessible through the bulk of Apple's installed base of 2.5 billion devices, but hundreds of millions of consumers have been chatting with apps from…