iOS 4 was the most popular mobile OS prior to launch of iOS 5. Launched in first half of 2010, this OS broke ground on several issues. Up to seven e background processes, introduction of multitasking, enhanced mails, better encrypted emails, SSL VPN support, iBooks, social gaming were among many exciting new features which were introduced.
If too many applications are bothering you, you can use home page folders. You can place one app on top of another and create a folder. Tap the folder to open and access the applications inside. You can keep similar apps together in this way and keep your home screen look clean and neat.
It also supported a new ‘unified mailbox’ setup. It means you can manage multiple mailboxes under the inbuilt mailbox. Here you can set up all your inboxes and can send and receive from all of them at the same time. No need to shift from one account to another manually.
The stock 27 wallpapers look really cool and colourful. You can choose from your camera also, the photos you have taken with it. Moreover, you can customize the lock screen and touch screen both together or differently.
The camera was improved too as the new OS allowed a 5x digital zoom for the camera.
Geotagging was introduced by this OS. In Geotagging, a photo taken with the camera automatically carries the location data where it was shot. If you don’t want to use this feature, you can conveniently turn it off.
With more minor adjustment, iOS 4 won the heart of the user in no time.
With almost 50 million iPhones sold prior to the release of iOS 4, almost half of them upgraded to iOS 4 and all the later devices came out with iOS 4 till the launch of iOS 5, which made iOS 4 the most successful OS of its time.