The iOS 7 operating system is not available yet to the public. But developers, who create the apps that run on Apple's devices, were given the chance to see the main changes for themselves.
At first glimpse, the most obvious change is the appearance, an edge-to-edge look that makes more use of translucency. There are new typefaces and new icons.
Apple also revealed that Siri, the voice-activated personal digital assistant, will come with all new male and female voices, a new look, and is now directly integrated with the Bing search engine.
The launch of iOS7 came as Apple announced the arrival of iTunes Radio, a service expected to rival the likes of Spotify.
The free Internet radio service will feature more than 200 stations and offer users an experience based on the music they listen to or download.
Apple has also integrated its Siri feature into iTunes Radio to allow users to ask questions relating to the tracks they listen to, such as the name of an artist.
Some industry experts have been criticizing Apple's mobile software, which has retained its general look and feel since its inception, for looking somewhat dated.
Apple boss Tim Cook is under pressure to show that the company is not slowing down as competitors such as Samsung and Google try and take a greater share of the market.
Apple's App Store now has 900,000 apps, which have been downloaded more than 50 billion times.
Stuart Miles, founder of technology and gadget site Pocket-lint, said Apple appeared almost more confident than ever before.
Ernest Doku, a telecoms expert at website uSwitch.com, added: