Apple announced i OS 4 in March, 2010 and it was released to the public on June 21, 2010 alongside the i Phone 4.With this release, Apple dropped support for the original i Phone and i Pod touch, the first time they had done this.i OS 4 was the first major i OS release that reflected the name change.
June 2007 saw the official first version release of what eventually became i OS – concurrently with the first i Phone.
i OS did not have an official name until the official release of the i Phone software development kit (i Phone SDK) on March 6, 2008.
i Phone OS 3 was compatible with all i OS devices released up to that time, but not all features were available on the original i Phone.
The final release supported on the original i Phone and i Pod Touch is i Phone OS 3.1.3.
The release of i OS 4.3 brought i Pad 2 compatibility.
Apple did not drop support for any devices with this release, as this had already been done with the release of i OS 4.3 seven months earlier.No official name was given on its initial release; Apple marketing literature simply stated the i Phone runs a version of Apple's desktop operating system, OS X.Apple announced i Phone OS 2, at the i Phone software roadmap keynote in March, 2008, and it was released to the public on July 11, 2008 alongside the i Phone 3G.Major new i OS releases are announced yearly during the Apple Worldwide Developers Conference (WWDC), and are usually released in September of the same year, usually coinciding with the release of new i Phone models.The current stable release, i OS 11.2.5, was released on January 23, 2018.i OS 6.1.6 is the final release supported for the i Phone 3GS and i Pod Touch (4th generation). Apple announced i OS 7 on June 10, 2013 at its annual Apple Worldwide Developers Conference (WWDC) event, and it was released to the public on September 18, 2013 alongside the i Phone 5C and i Phone 5S.