The Daily Hallucination

CUPERTINO, Calif. — Apple is developing a feature that would automatically lock an iPhone the moment it detects that the device has been violently snatched from its owner's hand, according to code discovered in a new iOS beta, and early testers say it is extremely good at detecting that and also several other things.

The feature, referred to internally as AutoLock, uses the phone's accelerometer and gyroscope to identify the sharp motion of a street theft, and can also lock the device if it loses contact with its owner's Apple Watch.

"The system is designed to recognize a grab," said a person familiar with the project. "It is still learning the difference between a grab and a toddler, a golden retriever, a spin instructor yelling 'climb,' and a man in Boston hailing a cab."

According to an informal tally of 1,100 beta testers compiled by the Apple enthusiast forum Tapline, the phone locked itself an average of 6.4 times per day, most often during workouts, on escalators, while being handed to a friend to look at a photo, and once during a particularly emotional reading of a text message.

"I tossed my phone onto the couch, like I do every night," said Marisol Achterhof-Nwosu, 36, a nurse in Oakland. "It locked, sent a notification to my watch, and my watch asked me if I was safe. I was sitting right there. We had a long conversation about trust."

The code also contains protections against false alarms, including a check for Face ID and for activity in the foreground app. Testers said those protections work well as long as the thief is also the owner, and is looking at the phone at the time.

Security researchers praised the effort. "A thief who grabs a phone and runs now gets a locked brick," said one. "An owner who grabs a phone and runs, for example to catch a train, gets the same thing, which I would call fair."

At press time, a man in San Francisco had been locked out of his own phone three times while trying to report that his phone kept locking.