IOS
A few months later, with the release of the iPhone 3GS, VoiceOver was added to iOS. When the iPod touch was upgraded to match the hardware of the iPhone 3GS (in iPod touch's third generation), it also gained VoiceOver capability. The iPad, since its introduction, has also had VoiceOver capability.
VoiceOver on iOS interacts with the user by using various "gestures", - different motions one makes with one or more fingers on the display. Many gestures are location-sensitive - for example, sliding one's finger around the screen will reveal the visual contents of the screen as the finger passes over them. This enables blind users to explore the actual on-screen layout of an application. A user can double-tap - similar to double-clicking a mouse - to activate a selected element, just as if a sighted user had tapped the item.
VoiceOver can also turn off the display but leave the touch screen sensitive to touch, saving battery power. Apple calls this feature "Screen Curtain". It is also available on Mac computers running OS X.
VoiceOver for iOS is activated using the "Settings" application. It can be found in the Accessibility section under the General section. The device can also be configured so that VoiceOver can be toggled by a triple-click of the Home button on the device.
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