Apple has crafted a development environment that is more conducive to producing high-quality polished apps with relatively little effort. The iOS SDK is a refined version of the Mac Cocoa SDK, which they have been developing for 10 years. They were able to keep the best qualities of standard Cocoa while further refining the framework for a mobile device. The end result is an SDK that not only has attracted tons of developers, but is also really enjoyable to work with.