Apple could launch iOS 8 and OS X10 and this would allow developers the option to see what is new in the operating system. This will then give them a good idea about updating existing apps along with the creation of new ones.
When Apple generally launch a new operating system they do it with a new iPhone and so people think that day two could be when we see the new iPhone 6.
It has been said this year Apple could launch two versions of the iPhone. It has been said that one of these will have a display of 4.7 inches, while the other may have a display of 5.5 inches. If so this would be the first time that Apple has launched a handset with a display this big.