"Greg has been planning to retire later this year after nearly 20 years at Apple Inc.," an official said in an email yesterday, saying he had made vital contributions to Apple Inc.
Christie was part of the team that developed the iOS software for the first iPhone, which came out in 2007.
Christie was until now leading a team working on a so-called human interface team developing more software for Apple Inc.
His role will be taken over by the current vice president for design, Jonathan Ive.
Ive in recent years has been working on Apple products' external look.
But industry publications say he has played a major role in developing the latest version of the iPhone operating system iOS 7.