Your comprehensive guide to Apple’s new iPhone 4

Tech giant Apple has finally announced the fourth-generation iPhone at the Worldwide Developer’s Conference in San Francisco, with a high-resolution screen and second camera among the gadget’s main features.

The phone is identical to the one seen in various leaks over the past few weeks, with chief executive Steve Jobs even referencing the now-infamous Gizmodo leak during his keynote by joking that “there have been a few photos around”.

But he also said the company was going to “take the biggest leap since the original iPhone” with the new gadget.

A sleek new design, an updated camera, internal hardware upgrades and a reduction in size are among the most prominent of the new iPhone’s over 100 new features.

But the keynote wasn’t just about the iPhone. Jobs took some time to brag about the company’s two million iPad sales, and said it now controls about 22% of the eBooks market. Over five million eBooks have been downloaded through the iBook Store, with over 35 million app downloads.

While the keynote left out some expected announcements, including the addition of web-based streaming to iTunes and an Apple TV upgrade, developers were rewarded with some impressive new hardware.

Here’s a comprehensive guide for all you need to know about Apple’s new iPhone 4.

New Design

The most obvious new feature of the iPhone 4 is the upgraded look. According to Apple it is “the thinnest smartphone on the planet” with a 9.3mm diameter – that’s 24% thinner than iPhone 3GS.

The curved back on previous iPhones has been replaced with a thick body. The front and black plates are now solid glass, with the edge made up of stainless steel.

But that casing isn’t just for good looks – it’s actually part of the phone’s hardware system. The steel edging serves as an antenna, assisting Bluetooth, Wi-Fi, GPS, UMTS and GMS signals. While Jobs says it’s usually not in the company’s style to allow uneven edges in a final design, in this case it’s an example of “brilliant engineering”.

Retina display

The new iPhone 4 has been upgraded with a new high-resolution display that can actually show more pixels than the human eye can comprehend – Apple calls it the “retina display”.

In his keynote, Jobs pointed out the human eye can only comprehend about 300 pixels per square inch. The iPhone 4 screen displays over 320, allowing for high-definition video and reading books through the new iBooks for iPhone app.

Apps already available on the App Store will be upgraded to higher resolutions, but Jobs says developers can update their programs to make them look even better than an automatic update would allow.

“It makes it so your apps run automatically on this, but it renders your text and controls in the higher resolution. Your apps look even better, but if you do a little bit of work, then they will look stunning.

The display itself is 960×640 with an 800:1 contrast ratio, and is powered by IPS technology. Some analysts predicted an OLED update, but Jobs says the IPS-powered screen is preferable.

The A4 chip

The iPhone 4 is powered by Apple’s very own A4 processor, allowing an improvement in battery life.

The Li-On battery takes up roughly 50% of the hardware space, allowing seven hours of 3G talking time, six hours of 3G browsing, 10 hours of Wi-FI browsing, 10 hours of video, 40 hours of audio and 300 hours of standby.

Jobs also mentioned dual microphone suppression technology, quad-band HSPDA of up to 7.2mbps and, surprisingly, only 32GB of hardware space. Some analysts were expecting an upgrade to 64GB.