The iPhone 4 runs Apple's iOS(first called iPhone OS)operating system which is present in all advanced Apple devices intended for consumer usage,such as the iPod Touch and iPod Touch 2.0 media player,the iPad tablet computer,as well as all other iPhone generations.The control of the iPhone 4,like in the case of older iPhone models,is built around the device's multi touch sensitive display screen,which allows users not only to user their bare finger on the display,but also use several fingers at the same time, for certain functions that require more than one finger. Such a function is the zooming function on the iPhone,which can be executed by two fingers on documents or web pages. The iPhone 4 has only two physical buttons,the rest of them being implemented in the multi touch sensitive display. The physical keyboard is also missing,as Apple decided to add a virtual keyboard.
The first available physical button on the iPhone is the Home button. By pressing this button,the device will close every opened application and redirect the controlling user to the Home screen where all applications are available for executing. The second button is the Awake/Sleep button. The primary duty of this button is to turn the device on or off .However,it can assure auxiliary tasks as well,such as changing the phone's mode to silent when pressed during an incoming call.
Even tough the iPhone 4 has all the characteristic features of the original iPod, like screen zise or button placement,it comes with some updates and upgrades of it own,and the most noticeable difference between it and its predecessors is the phone's new design. This model incorporates an uninsulated stainless steel frame which acts as the iPhone's antenna. The iPhone 4's hardware was upgraded as well,as it is composed of an A4 processor,512 MB of eDRAM which is double the size of this model's predecessors and four times the size of the original model.
The phone has a 3.5 inch liquid crystal display (LCD) which is marketed as 'The Retina Display' due to its high resolution of 960x640. Some iPhone 4 buyers have complained about the phone losing signal when it is held in different ways,especially when held in the left hand.Apple resolved this problem by offering the unhappy customers free cases that fixed the problem or the possibility of a refund in 30 days after the purchase.