Programming the iPhone User Experience

The Devices

The screen on both the iPhone and iPod Touch is an LCD-lit 3.5-inch (diagonal) widescreen Multi-Touch display. The screen resolution is 480×320 pixels at a resolution of 163 pixels per inch. The devices include the following sensors: accelerometer, proximity sensor, and ambient light sensor.

• When activated, the accelerometer is used to detect device movement in space, providing information about movement along three axes.

• The proximity sensor recognizes the proximity of the handset to another object, most commonly a human ear.

• The ambient light sensor detects the level of ambient light hitting the device.

Both the iPhone and iPod Touch devices provide rocker switches for controlling volume, a hardware power button, and a depressible “home” button. These concrete interfaces are outside the scope of Cocoa Touch programming, but are notable in the overall UX (user experience) of the devices.

From the point of view of user experience programmers, the hardware interface elements are separate from the touch interface. Apple doesn’t provide any means of accessing the home button, lock button, volume controls, or the navigation controls included on headsets. This simplifies the domain of UX programming, but comes at a cost: there are certainly cases in which access to the home button or volume rocker could provide enhanced functionality to users.

The iPhone provides a few distinct advantageous features over the iPod Touch, aside from the telephony. For example, the iPhone includes GPS support and a hardware ringer/silence switch. For networking, in addition to 802.11g support, the iPhone 3G includes support for 3G wireless networking, and support for High-Speed Downlink Packet Access (HSDPA). The operating system will, unless told otherwise, automatically switch from 3G to wireless networks with known names. This feature is part of a larger UX pattern that is core to the iPhone: attempting to deliver the best experience possible given the environment, without interruption. We will cover this pattern in Chapter 8.