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.
– Tim Cook, Apple CEO
The team at Apple has been working incredibly hard on the latest version of iOS and today it is of great thrill that I announce iOS 7.
iOS 7 is the biggest change to iOS since the introduction of the iPhone.
It's packed with amazing new features and a stunning new user interface.
– Sir Jonathan Ive, Apple design chief
We see iOS 7 as defining an important new direction and in many ways a beginning.
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 statement
The more you use iTunes Radio and iTunes, the more it knows what you like to listen to and the more personalised your experience becomes.
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.
I think they came across as being a calm and confident Apple, setting themselves up for the next ten years.
There were lots of features borrowed, refined and improved with iOS 7 that are sure to make everybody love it again.
It's a very colourful, playful operating system, from what I have seen so far, which may not appeal to everybody - it is perhaps more fun than geared towards business use - but I think that is what people want.
They want the fresh take on something they are familiar with and Apple have certainly given them that.
Ernest Doku, a telecoms expert at website uSwitch.com, added:
With many elements of Apple's six-year old operating system showing their age - and stiff competition from the visually arresting charms of Android and Windows Phone 8 - the crow's feet had started to become visible on its range of hugely popular devices.
With iOS 7, Apple was eager to show this wasn't just a fresh coat of paint, or a few nips and tucks. Jony Ive and his team have really brought the design ethos that have made Apple products so iconic on the outside, and seem to have revamped the innards just as drastically too.