Touch screen

The 3.5 inch (8.9 cm) liquid crystal display (320×480 px at 160 ppi) HVGA touch screen topped with optical-quality glass is specifically created for use with a finger, or multiple fingers for multi-touch sensing. No stylus is needed, nor can an ordinary one be used, as the touch screen requires touch by something with the physical properties of bare skin to operate. For text input, the device implements a virtual keyboard on the touchscreen. It has automatic spell checking, predictive word capabilities, and a dynamic dictionary that learns new words. Notably, the predictive word capabilities have been integrated with the dynamic virtual keyboard so that users will not have to be extremely accurate when typing — i.e. touching the edges of the desired letter or nearby letters on the keyboard will be predictively corrected when possible. Additionally, an optional landscape mode for text entry with the virtual keyboard has been mentioned by Apple executives as a possibility for iPhone, but Apple has not yet come to a final decision as to its inclusion in the shipping version of iPhone. A possible advantage of landscape text entry would be the availability of larger keys to ease text entry, especially for individuals with larger fingers. The iPhone varies from common desktop interfaces by using a direct manipulation model of scrolling. Where a typical desktop GUI achieves scrolling by using a scroll-arrow to push a view-window down and thus the content itself up (or the reverse, clicking up to move content down), the iPhone interface enables the user to move the content itself up or down by a touch-drag-lift motion of the finger, much as one would slide a playing card across a table. Additionally, the speed desired for scrolling is computed based on the speed and acceleration with which the drag motion is performed.Scrolling through a long list works as if the list is pasted on the surface of a wheel: the wheel can be "spun" by sliding a finger over the display. After the finger is lifted from the display the wheel continues to "spin" for a short moment before coasting down. In this way, the iPhone seems to simulate the physics of a real object, which, it is thought, should give a natural feel to the whole process.