iOS

iOS from Apple Inc. (closed source, proprietary, on top of open source Darwin core OS)

The Apple iPhone, iPod Touch, iPad, and second-generation Apple TV all use an operating system called iOS, which is derived from Mac OS X. Native third party applications were not officially supported until the release of iOS 2.0 on July 11th 2008. Before this, "jailbreaking" allowed third party applications to be installed, and this method is still available. Currently all iOS devices are developed by Apple and manufactured by Foxconn or another of Apple's partners.