Apple founder Steve Jobs had one strict rule for the secret team building the

first iPhone

: don’t talk about it. The project, known as

Project Purple

, was kept secret—even within Apple. In a 2017 interview with

The Wall Street Journal

, former Apple executives recalled how the mission to build the iPhone was unlike anything else they’d ever done. “We put a poster up on the wall,” said Scott Forstall, Apple’s former senior vice president of iOS. “The first rule of Project Purple was you don’t talk about Project Purple.” The team likened their experience to the movie

Fight Club

, operating in isolation and under extreme pressure.According to the team, most Apple employees had no idea what was going on. Hardware and software teams worked separately, and information was tightly controlled. “Not one person knew what iPhone was gonna look like right before that keynote,” said Greg Christie, former Apple software designer. “People thought they knew that Apple was doing the phone, but nobody knew what they were going to see that day.”Forstall described the grueling pace. “168 hours a week for two weeks,” he said, referring to the intense sprint that locked in the iPhone’s user interface. The team worked nonstop, scrapping early iPod-like designs and shifting toward something completely new.

A Benzinga report quotes Tony Fadell, one of the key minds behind the iPod and the iPhone, who said early versions were clunky. A major breakthrough came when Jobs asked if their multitouch screen, originally meant for a tablet, could be used on a phone. The first demo was huge—“It was like a Big Mac,” Fadell said.The on-screen keyboard turned out to be one of the hardest parts to perfect. Forstall said he paused all other interface development until the keyboard worked properly. Dozens of versions were created. Eventually, an engineer’s predictive typing system was chosen—and it still forms the basis of iPhone keyboards today.