iOS does not belong to Apple, but is instead licensed from Cisco, who owns the trademark.
The operating system was unveiled with the iPhone at the Macworld Conference & Expo, January 9, 2007, and released in June of that year. At first, Apple marketing literature did not specify a separate name for the operating system, stating simply what Steve Jobs claimed: “iPhone runs OS X” and runs “desktop applications” when in fact it runs a variant of Mac OS X, that doesn’t run OS X software unless it has been ported to the incompatible operating system. Initially, third-party applications were not supported. Steve Jobs’ reasoning was that developers could build web applications that “would behave like native apps on the iPhone”. On October 17, 2007, Apple announced that a native Software Development Kit (SDK) was under development and that they planned to put it “in developers’ hands in February”. On March 6, 2008, Apple released the first beta, along with a new name for the operating system: “iPhone OS”.
Apple had released the iPod Touch, which had most of the non-phone capabilities of the iPhone. Apple also sold more than one million iPhones during the 2007 holiday season. On January 27, 2010, Apple announced the iPad, featuring a larger screen than the iPhone and iPod Touch, and designed for web browsing, media consumption, and reading iBooks.
In June 2010, Apple rebranded iPhone OS as “iOS”. The trademark “IOS” had been used by Cisco for over a decade for its operating system, IOS, used on its routers. To avoid any potential lawsuit, Apple licensed the “IOS” trademark from Cisco.