But sources inside Apple say that the move is not acrimonious, with Christie due to leave by the end of the year rather than immediately, as would be expected if he had been forced out. However Ive and Christie are said to have disagreed on some design decisions for software – a field which Christie had worked on for 20 years.
The move comes at a critical time for Apple, asx it is preparing to finalise elements of the next version of its iOS software, iOS 8, ahead of an expected public unveiling at its Worldwide Developers Conference (WWDC) in June in San Francisco, and full release in autumn this year.
The introduction of the radical redesign of iOS 7 last year was the first time that Ive had been deeply involved in software design, having led the product and hardware design teams for more than a decade. Ive was promoted after Scott Forstall, who had led the iOS group from its inception, was fired by chief executive Tim Cook after the debacle over the introduction of Apple's Maps app in September 2012.
The iOS 7 redesign rejected "skeuomorphism" - making onscreen objects mimic the appearance of real-life ones, such as calendars, baize gaming tables or lined note paper - and Ive called it "an important new direction".
Prolific in patents
Christie joined Apple in 1996 to work on its ill-fated Newton "personal digital assistant", but then remained to become a key player in its software side, surviving a wide-ranging clearout of existing staff when Steve Jobs returned and took over the company in 1997. He is listed as an inventor on nearly 100 patents, and has a further 31 pending approval at the US patent office.
Christie's departure was first revealed by 9to5Mac, which said the departure was due to "friction" between Ive and Christie after the British designer was given overall responsibility for both hardware and software design at the end of 2012. The site said that the redesign of the iPhone and iPad software to produce iOS 7, released in September 2013, led to clashes over design direction and that Ive "circumvented Christie's leadership of the team during the new operating system's development".
But sources at Apple signalled that Christie's departure was less dramatic, and that after 18 years at the company he had decided to retire and cash in his shares. Sources say that Christie's departure had been announced inside the company some weeks earlier, and according to Techcrunch had been "planned for even longer… to allow for a transition of leadership inside the Human Interface group."
In a statement, Apple said: “Greg has been planning to retire later this year after nearly 20 years at Apple. He has made vital contributions to Apple products across the board, and built a world-class Human Interface team which has worked closely with Jony for many years.”
Christie testified as one of the key designers behind the "slide to unlock" patent at the ongoing Apple-Samsung trial in San Jose last week, and also gave interviews about the process of designing the iPhone to the Wall Street Journal and NPR.
He has been seen as critical in the design both of iOS 7 and of Apple's desktop software Mac OSX.
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