Mr. Williams was long considered a leading candidate to replace Tim Cook as the company’s next chief executive.

Having worked at Apple for nearly three decades, Williams has played a significant role in introducing the iPod and iPhone programs, leading the development of the Apple Watch, and overseeing the design team,

Here’s the outgoing Apple COO and defacto head of design recounting the time that Steve Jobs willed a scratch-resistant display into existence after the original iPhone was announced with a plastic screen.