Forstall has played an important role as senior vice president of iOS software and has been a high-profile figure at the company, often sharing the stage with the late CEO Steve Jobs and other executives at mobile product launches. Prior to his departure next year, he will serve as an adviser to CEO Tim Cook.

Craig Federighi, senior vice president of Mac Software Engineering, will now lead both iOS and OS X development. Apple said the change would "make it easier to deliver the best technology and user experience innovations to both platforms."

In retail, the search for a new chief is now under way, Apple said.

Forstall's and Browett's departures were announced as part of a broader reshuffling at the highest levels of Apple management. The company said the changes would encourage more collaboration among its hardware, software and services teams.

In addition to Federighi, three other top executives are taking on more responsibilities.