Mark Gurman and Min Jeong Lee, Bloomberg:

Apple is preparing three iPhones for launch as soon as this fall, including upgraded versions of the current two iPhone models and a new top-of-the-line handset with an overhauled look, according to people familiar with the matter. For the redesigned phone, Apple is testing a new type of screen, curved glass and stainless steel materials, and more advanced cameras, the people said. Those anxiously awaiting the redesigned iPhone, however, may have to wait because supply constraints could mean the device isn’t readily available until one or two months after the typical fall introduction.

Lots of fascinating details here, all provided by people familiar with the matter.