Interface

The display responds to three sensors: a proximity sensor that shuts off the display and touchscreen when the iPhone is brought near the face to save battery power and to prevent spurious inputs from the user's face and ears, an ambient light sensor that adjusts the display brightness which in turn saves battery power, and a 3-axis accelerometer, which senses the orientation of the phone and changes the screen accordingly. Photo browsing, web browsing, and music playing support both upright and left or right widescreen orientations, while videos play in only one widescreen orientation.

A single "home" hardware button below the display brings up the main menu. Subselections are made via the touchscreen. The iPhone utilizes a full-paged display, with context-specific submenus at the top and/or bottom of each page, sometimes depending on screen orientation. Detail pages display the equivalent of a "Back" button to go up one menu.

The iPhone has three physical switches on its sides: wake/sleep, volume up/down, and ringer on/off. All other multimedia and phone operations are done via the touch screen.

The iPhone interface enables the user to move the content itself up or down by a touch-drag motion of the finger, much as one would freely slide or flick a playing card across a table with a finger. Similarly, scrolling through a long list in a menu works as if the list is pasted on the outer surface of a wheel: the wheel can be "spun" by sliding a finger over the display from bottom to top (or vice versa). In either case, the object continues to move based on the flicking motion of the finger, slowly decelerating as if affected by friction. In this way, the interface simulates the physics of 3D objects, giving it a real world feel.

The photo album and web page magnifications are examples of multi-touch sensing. It is possible to zoom in and out of web pages and photos by placing two fingers (e.g. thumb and forefinger) on the screen and spreading them farther apart or closer together, as if stretching or squeezing the image. As can be expected from multi-touch sensing, the two fingers don't have to be from the same hand.