Inside story of the iconic iOS rubber band effect that launched the iPhone

An except from Leander Kahn’s book on Apple interface designer, Bas Ording recalling the rubber band effect:

The first thing Jobs says is that the conversation is super-secret, and must not be repeated to anyone. Ording promises not to.

“He’s like, ‘Yeah, Bas, we’re going to do a phone,’” Ording told Cult of Mac, recalling that momentous call from long ago. “‘It’s not going to have any buttons and things on it, it’s just a screen. Can you build a demo that you can scroll through a list of names, so you could choose someone to call?’ That was the assignment I got, like pretty much directly from Steve.”

However, as he worked on his scrolling list, Ording noticed that when he got to the bottom or the top of the list it just stopped. He’d pull the list down but it would just sit there. It looked like it had crashed. Every time he saw it, it bugged him, but he didn’t know how to fix it.

He tried adding some space at the top. When he got to the top of the list, the small space would appear. But that didn’t solve the problem — it just repeated it.

The space just sat there, unmoving.

Ording figured the space would need to move with the user’s finger to show that it was still responsive. But that didn’t feel right, so Ording tried making it move more slowly than the user’s finger, just as an experiment. The effect was to make it feel elastic.

“I’m like, ‘Ooh this is kind of fun,’ and then, ‘Oh wait, now it needs to move back,’” Ording said.

When he made it snap back, it acted like a rubber band — it moved down, but then bounced back to its correct position.

Fascinating excerpt into a feature we use every day and take for granted which shows the delight in the details of design.