History of Apple Inc.
The first version of the iPhone became publicly available on June 29, 2007 in selected countries/markets. It was another 12 months before the iPhone 3G became available on July 11, 2008. Apple announced the iPhone 3GS on June 8, 2009, along with plans to release it later in June, July, and August, starting with the U.S., Canada and major European countries on June 19. This 12-month iteration cycle has continued with the iPhone 4 model arriving in similar fashion in 2010, a Verizon model was released in February 2011, and a Sprint model in October 2011, shortly after Jobs' death.
IPhone 4
The iPhone 4 spent the longest time as Apple's flagship iPhone model at fifteen months. Although the succeeding 4S was announced in October 2011, the 4 continued to be sold as a midrange model until September 2012, and thereafter as the entry-level offering in Apple's lineup until September 2013 with the announcement of the iPhone 5S/iPhone 5C. The iPhone 4 had the longest lifespan of any iPhone ever produced, spanning close to four years and available in some developing countries until early 2015.