Apple has launched its “most advanced” smartphone yet with the iPhone 14, which features battery life and camera upgrades over its predecessor.

Its four new models are between 6.1 and 6.7 inches in length, meaning they have larger screens than the iPhone 13, while lasting all day on a single charge.

However, one expert noted that Apple had reserved the “biggest leaps” – such as a more powerful processor – for the Pro, its more expensive handset.

The iPhone 14 and 14 Plus feature an upgraded 12MP camera, while the Pro and Pro Max have a 48MP camera.

All are equipped with a larger light sensor which can produce low-light photographs twice the previous generation’s quality.

Apple launches iPhone 14
A person takes a photo of a new iPhone model at Apple’s California HQ (Jeff Chiu/AP)

“Low-light photography has always been a challenge given the sensor size in mobile phones,” Ru Bhikha, mobiles expert at Uswitch.com, told the PA news agency.

“So any sort of improvements there, given the amount of pictures we take on a daily basis, will definitely be seen as a worthy upgrade compared to the iPhone 13.”

However, while the standard iPhone 14 uses its predecessor’s A15 bionic chip, the Pro will be equipped with the faster A16 chip.

“Apple has stuck to its guns and reserved its biggest leaps in innovation for its most premium handsets, despite the economic challenges facing many consumers,” Mr Bikha noted.

Similarly, the Pro versions boast an “Always-On Display”, meaning users can see basic notifications while the screen is locked.

Unveiling the feature at a virtual event, Apple executive Greg Joswiack said: “It’s easy to see the time and other core information without raising your iPhone or tapping the display.

“This keeps the central information available for the moments where all you need is just a glance… this is the most advanced display we’ve ever shipped.”

Mr Joswiack added that it was made possible by the Pro’s “incredibly power-efficient” display, which operates with a refresh rate as low as 1Hz.

Apple has ditched the iPhone mini seen in previous generations – the “cheapest and most pocket-friendly phone from the main series”, Mr Bikha said.

The virtual event also saw the unveiling of the Apple Watch Ultra, which the company’s chief operating officer Jeff Williams labelled “the most rugged and capable Apple Watch yet”.

It is aimed at those taking part in extreme sports – such as deep-sea diving – and is fortified by titanium casing and a sapphire crystal display protector.

The iPhone 14 will be available for £849 on September 16, while the Plus will appear on shelves for £949 on October 7.

The Pro and Pro Max retail for £1,099 and £1,199 on September 16 and 23.