Apple's newest operating system update to the iPhone, the iPad and the iPod Touch, called iOS 5, is available to download from Wednesday.

iOS 5 brings an entirely new notifications system, a BlackBerry Messenger-rivaling free messaging app, systemwide Twitter integration and increased performance, giving users the feeling of a brand new phone.

iOS 5
Apple

The software update is free and brings more than 200 new features to the iPhone, the iPad and the iPod Touch, including a location-aware reminders app, Newsstand and wireless syncing. The update aims to separate the iDevice from the personal computer, with what Apple is calling "PC Free," meaning any iOS 5 device can be operated entirely without a computer, finally making the iPad a true netbook competitor.

iOS 5 is compatible with iPhone 3GS, iPhone 4, iPad, iPad 2 and iPod Touch third and fourth generation.

Notification Centre

Notifications have been pushed to iOS devices for a few years now, but they provided little information, forcing the user to quit what they're doing and go to the relevant app requesting attention. Now, though, all notifications are displayed in a panel that can be accessed by swiping down from the status bar, whether you're at the home screen, or in an app already.

This swipe-down panel is very similar to that found on Android phones, but it carries the usual Apple garnish of a slightly textured background and a share price ticker scrolling from right to left.

The notification centre can be customised to show a ticker of your share prices, the local weather and, of course, notifications from the phone, mail, messages, Facebook, Twitter and any other apps that demand your attention. Previews of messages and e-mails are shown, and the notification can be acted upon by tapping it.

iOS 5 Notifications

Earlier, notifications always appeared in the same way an SMS-style box in the centre of the screen that had to be dismissed before being able to do anything else. With iOS 5, notifications can be set to appear as a small message at the top of the screen, which doesn't interrupt what you're doing. Games don't pause, for example, and the box disappears after a few seconds.

The lock screen has also been tinkered with, showing a clearer list of any calls, messages, and e-mails that have been received while the phone has been locked. Swiping over a text or email takes you right to the relevant app.

iMessage

In a move that will no doubt annoy BlackyBerry users, who have suffered days of network problems, Apple has brought a free messaging system to iOS, mimicking the popular BlackBerry Messenger.

You can read out up-to-date news on the BlackBerry network outage here.

iMessage is available exclusively to iOS 5 users and is built right into the current messaging app. Text messages from users who have iOS 5 (and a data connection) will appear in blue instead of the usual green for text messages. Choosing between a text message and an iMessage requires no input from the user at all; if the phone has a data connection -- be it GPRS, EDGE or 3G -- and the recipient has iOS 5, then text messages will be sent as free iMessages.

Delivery reports are included and an icon appears on screen to show when the recipient is typing a new message.

Text, images and video can be sent as iMessages, which is great news for anyone who doesn't have an unlimited text plan, or for those with an iPod Touch, who can now send messages to iPhone, iPads and other iPod Touches free of charge -- providing they have a Wi-Fi connection.

iMessage could well be a killer blow for BlackBerry, with BBM arguably the most popular feature among non-business users. With the recent data blackouts and iPhone 4S announcement, iMessage might convince users to move away from BlackBerry.

Reminders

There's a whole range of to-do list apps available for the iPhone, but Apple has decided to make their own and include it with iOS 5.

Simply add something to be reminded of -- buy some milk, for example -- set a time, and you're done. A notification just like any other will appear - along with an alarm if you so wish - at the time the user sets.

iOs 5 reminders

What sets Reminders apart from the crowd is that it's location-aware. If you want to get that milk after work you can set Reminders to notify you when you leave work -- providing you have GPS turned on and you have work set as a contact in your address book.

Having to select a location from the address book is a pain; hopefully the ability to drop a pin on a map and select that as a location to be reminded at will be available in a future update.

Twitter integration

While Android offers great Facebook integration, Apple has gone down the other social networking group and got into bed with Twitter. The result is that, once signed into the microblogging service, Twitter is available systemwide, letting you tweet links and photos from anywhere in the iDevice, and attach your current location, too. Any contacts who appear on Twitter and in your address book will be synced together, automatically attaching Twitter handles to the correct contacts.

Safari

Reader is a new feature of Safari, letting users save Web pages to read later, offline. Your reading list is kept up-to-date between all iOS devices. Fully tabbed browsing is coming to the iPad, so navigating between tabs takes just one tap instead of two.

Volume up as camera shutter

The iPhone has always been criticised for having an on-screen shutter button for the camera app. The button is awkwardly placed and difficult to press while holding the phone still. Apple has finally noticed this and has given users the option to take a photo using the volume up button, which is located roughly where the shutter button would be. The only downside is now the lens isn't where it would be on a conventional camera. It's under your hand. Not ideal, but at least now users have the option, and in testing we found that clicking a physical button is better than tapping the screen.

Ability to access camera app from lock screen

Apple wants more people to take photos with the iPhone 4 and 4S -- despite the 4 already being the most popular smartphone on Flickr -- and to speed this it's now possible to access the camera app from the lock screen.

Click the home button twice when the iPhone is locked and an icon appears next to the slider; tapping this opens the camera app. This even works if your iPhone is locked with a passcode, but don't worry, nothing else can be viewed apart from the photos taken at that moment, and the passcode is still needed to access any other part of the phone.

Wi-Fi Sync

iOS 5 lets devices sync wirelessly with the computer that they're paired with. So just plug your iPhone into its charger at night and Wi-Fi sync does the rest, keeping your music, photos, contact and everything else up-to-date on your phone and computer - providing they're both turned on and connected to the same Wi-Fi network, obviously.

Devices with iOS 5 do not lock themselves while syncing, meaning that incoming text messages can be read, and the device works as normal, as syncing is done entirely in the background.

Over-the-air updates have finally made their way to iOS, meaning that the iPhone, iPad and iPod Touch can receive software updates wirelessly, without the need to be plugged into the computer with which they sync. Over-the-air updates are also significantly smaller due to only replacing updated elements of the device's firmware, not the entire operating system. A reminder badge appears on the Settings app when an update is available and it can be downloaded over 3G or Wi-Fi, providing the device believes it has enough batter power to complete the update.

Photo editing

Photos taken with the camera app can now be edited, with the ability to crop, apply red-eye reduction and auto-enhance photos, providing a quick and easy way to tidy up snapshots before sharing them.

Overall, iOS 5 brings some much-needed features to the iDevice range, and with the promise of a speed increase users will feel like they have upgraded their phone with more than just software. Those who own an iPhone 4 and are considering the 4S - due out on Friday - should give iOS 5 a try and decide then if this update is enough, without the full-fat upgrade of the new model.

The iPhone 4S is the only model to support Siri, Apple's new voice-controlled personal assistant. Sadly, that won't be available on the iPhone 4 or 3GS.

Updating the notifications system was much-needed, and iMessage is a welcome surprise, although only being supported on iOS 5 leaves owners of older models in the dark, despite it being a relatively basic application.

iOS 5 requires iTunes 10.5, both of which are now available to download for free.

Read more about iOS 5 here.

UPDATE: We're hearing that iOS 5 will be available to download from around 5:45pm BST in the UK, that's 9:45am Pacific and 12:45pm Eastern in the US.

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