IOS 8

iOS 8 is the  eighth release of the  iOS  mobile operating system designed by  Apple Inc, as the successor to  iOS7. It features new compatibilty with the upcoming OS X 10.10 "Yosemite" such as enabling Macintosh computers to intercept calls from your iPhone and be used to talk to the caller.iOS 8 was released on Wednesday September 17, 2014. It is compatible with:

IPhone 6 iPhone 6 Plus
 * iPhone 4S, iPhone 5, iPhone 5C, iPhone 5S
 * iPod Touch (5th generation)
 * iPad 2, IPad_(3rd_Generation), IPad_(4th_generation)
 * iPad Mini, IPad_Mini_with_Retina_Display IPad Air IPad Air 2

Use iOS 8 on iPhone 6 From OS X Yosemite.