The new software has been designed to make the iPhone appear bigger, with features crafted to take advantage of the entire screen.
Text is said to appear sharper, while a "control centre" on the phone allows users to adjust settings with just one swipe from the bottom of the screen.
This gives instant access to functions such as Airplane Mode, Wi-Fi, Bluetooth or Do Not Disturb, and enables users to quickly pause or play a song, jump to the next track and stream music.
Meanwhile a "notification centre" is available from the "lock" screen so users can view updates with a "simple swipe".
More top news
Beth Tweddle has begun walking unaided following neck surgery after injuring herself during training for TV reality show 'The Jump'.
Actor Bill Murray has offered to pay for the mobile phones of two fans he allegedly threw from bar after they tried to take photos of him.
Inadequate pain medication means cancer patients who want to die at home have no choice but to go to hospital, charity says.