The Computer History Museum Oral Histories are a wonderful project. They are deep, long, interviews with many different programmers. Lots of never-before-made-public details about important projects.
For example, this oral history by Oral History of Kenneth Kocienda and Richard Williamson goes into details of how iOS was designed:
Or if you prefer PDFs:
One of the interesting things I found out was that there was an attempt to use HTML/Web APIs to write iPhone apps, and that for the first two or three iOS releases some of the apps, including the Stocks and Weather apps were implemented as HTML/Web apps.