At a special press event Thursday in Cupertino, Apple revealed details of the official—and long-awaited—iPhone SDK. Building on the foundation of OS X and marrying it with a multitouch specific UI layer, Apple is calling the collection of APIs "Cocoa Touch." Included in the SDK are updates to Interface Builder and Xcode to enable development with the new APIs, as well as an iPhone simulator to test development from your Mac before debugging on the iPhone itself. In addition, debugging and profiling tools work from a Mac-connected iPhone.
The SDK includes everything you'd expect from an Apple environment, including the UNIX-based internals of OS X. In addition, developers will have access to Keychain, Bonjour, SQLite and Core Location as well as a mature, Quicktime-based media layer including video playback, Core Audio, Core Image, Core Animation, PDF rendering, OpenAL, and OpenGL ES. Cocoa Touch gives developers access to the hardware and interface, including Multi-Touch events and controls, Accelerometer, View Hierarchy, Localization, alerts, Web View, People Picker, Image Picker and the integrated Camera.
Link: Ars Technica Article