Apple:
Apple designed the iOS platform with security at its core. When we set out to create the best possible mobile OS, we drew from decades of experience to build an entirely new architecture. We thought about the security hazards of the desktop environment, and established a new approach to security in the design of iOS. We developed and incorporated innovative features that tighten mobile security and protect the entire system by default. As a result, iOS is a major leap forward in OS security.
While I can’t help but think that Apple’s trying to move past the goto fail; bug, there’s a lot of interesting stuff in this PDF.