iOS 7 is the seventh major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 6. It was announced at the company's Worldwide Developers Conference on June 10, 2013, and was released on September 18 of that year. It was succeeded by iOS 8 on September 17, 2014. User adoption of iOS 7 was fast. Its iOS market share was reported to be as high as 35% after one day, and installed on 200 million devices within 5 days, which Apple stated was "the fastest software upgrade in history."