iPhone 6 and iPhone 6 Plus unveiled by Apple

Apple has unveiled the latest generation of its iPhone smartphones - named the iPhone 6 and iPhone 6 Plus.

Apple CEO Tim Cook was centre stage to reveal the two different-sized versions of the iPhone 6 at the event in the Flint Center, California. The location is historic as the place where Steve Jobs first unveiled the Macintosh computer. Cook called it the "biggest advancement in the history of iPhone".

Apple announced that the iPhone 6 starts at $199 with a two-year contract in the US, going up to $299 or $399 for the respective models (16GB, 64GB, and 128GB).

The iPhone 6 Plus starts at $299 with a two-year contract in the US, going up to $399, or $499 for the 16GB, 64GB, and 128GB models respectively. Both versions come in gold, silver, or space gray.

Pre-orders open from 12 September, 2014. The phone will be available from 19 September in the UK, US, France, Hong Kong, Canada, Germany, Singapore, Australia, and Japan.

Both of the new iPhone 6 models feature a new Retina HD display.

The iPhone 6 has a 4.7in display with resolution of 1334 x 750 (326 pixels per inch).

The iPhone 6 Plus has a 5.5in display with resolution of 1920 x 1080 (401 pixels per inch).

Apple says the "Dual-domain pixels on the photo-aligned IPS display give you a wider angle of view."

Both devices will feature the powerful A8 processor chips, which Apple's Phil Schiller claims are 50% more power-efficient than A7 chips.

The new iPhones bear the distinction of being the thinnest yet from Apple. iPhone 6 is 6.9mm thick, and iPhone 6 Plus is 7.1mm thick. In comparison, the iPhone 5 is 7.6mm thick.

The iPhone 6 will feature an 8 megapixel camera, and boasts "True Tone flash" and "Focus Pixels" that apparently help the sensor focus faster and better.

The iPhone 6 is to feature a barometer which will sense air pressure and measure relative elevation - useful for fitness apps.

A new feature for the iPhone 6 and iPhone 6 Plus is called Reachability, which makes controlling a large device with one hand easier by allowing you to slide the screen around with one finger to reach different parts of it.

Schiller notes that there are now more than 1.3 million apps available for the iPhone. A new tool called Xcode makes it easier for software to scale. It also works on apps that haven't been updated yet.

Schiller said "These aren't only the best phones in the world but they're the best value as well."

Plus Size Models

The 4.7in and 5.5in iPhones will bring the company up to speed with Android offerings, which have seen the likes of Samsung, Sony, and HTC all produce flagships in the 4.5in to 5.5in range.

However, some analysts have suggested that current iPhone users are happy with their smaller device.

Detailed polling from Qriously found that less than a third of the 8,750 existing iPhone users polled in the UK would currently upgrade to the new flagship device.