"Apple has always looked out for kids, and we work hard to create powerful products that inspire, entertain, and educate children while also helping parents protect them online," a spokeswoman told Bloomberg. "We have new features and enhancements planned for the future, to add functionality and make these tools even more robust."

The letter, written by Jana Partners LLC and the California State Teachers' Retirement System, asked Apple to include more safety features in iOS that allow parents to monitor the use of a child's iPhone, citing cases of increased distraction and a higher risk of depression and suicide. Apple isn't solely to blame, given the availability of social-media apps, but it was also urged to conduct research into heavy use on young mental health.

While Apple does provide parental controls, they are focused on limiting access to adult apps, music and video -- an "all-or-nothing approach," the groups call it. "As one of the most innovative companies in the history of technology, Apple can play a defining role in signaling to the industry that paying special attention to the health and development of the next generation is both good business and the right thing to do," they argued.

Apple agrees, and it's likely we'll see more advanced parental controls come to iOS in the near future.