George Gascón, San Francisco’s district attorney, says handset makers like Apple should be exploring new technologies that could help prevent theft. In March, he said, he met with an Apple executive, Michael Foulkes, who handles its government relations, to discuss how the company could improve its antitheft technology. But he left the meeting, he said, with no promise that Apple was working to do so.

He added, “Unlike other types of crimes, this is a crime that could be easily fixed with a technological solution.”

Apple declined to comment.

The cellphone market is hugely lucrative, with the sale of handsets bringing in $69 billion in the United States last year, according to IDC, the research firm. Yet, thefts of smartphones keep increasing, and victims keep replacing them.

In San Francisco last year, nearly half of all robberies involved a cellphone, up from 36 percent the year before; in Washington, cellphones were taken in 42 percent of robberies, a record. In New York, theft of iPhones and iPads last year accounted for 14 percent of all crimes.

Some compare the epidemic of phone theft to car theft, which was a rampant problem more than a decade ago until auto manufacturers improved antitheft technology.

“If you look at auto theft, it has really plummeted in this country because technology has advanced so much and the manufacturers recognize the importance of it,” said Chuck Wexler, the executive director of the Police Executive Research Forum, a nonprofit group focused on improving police techniques. “The cellphone industry has for the most part been in denial. For whatever reasons, it has been slow to move.”

After Facebook and Twitter announced that they were breached by sophisticated hackers in recent weeks, Apple said it had been attacked, too, in a rare admission for the technology giant.

In a statement to reporters Tuesday, Apple said some of its computers were infected with the same malware that hit Twitter and Facebook. Like Facebook, Apple confirmed that its employees’ computers were infected with malware when they visited a Web site for software developers. Neither company has named the Web site. But according to a person with knowledge of Facebook’s investigation, the compromised site, iPhonedevsdk, an online forum for software developers, is still infected. (In other words, unless you want to be owned by hackers, do not visit the site.)

“We identified a small number of systems within Apple that were infected and isolated them from our network,” Apple said in a statement. “There is no evidence that any data left Apple. We are working closely with law enforcement to find the source of the malware.”

Twitter said attackers may have briefly accessed data for 250,000 user accounts and that it reset passwords for and alerted users whose data may have been vulnerable. Facebook said that no user data was taken in its attack. Both companies said that they were also working with law enforcement to trace the source of the attacks, which they described only as “sophisticated.”

In all three cases, the attackers exploited a well-known security hole in Oracle’s Java software. Java, a widely used programming language, is installed on more than three billion devices. It has long been hounded by security problems.