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<google>BUY_IOS4XC4</google>

In the chapter entitled [[Detecting iOS 4 iPhone Touch Screen Gesture Motions (Xcode 4)|Detecting iOS 4 iPhone Touch Screen Gesture Motions]] we looked at how to track the motion of contact with the iPhone screen. In practice, an application will need to respond to specific motions that take place during the course of a gesture. The swiping of a finger across the screen might, for example, be required slide a new view onto the display. Similarly, a pinching motion is typically used in iPhone applications to enlarge or reduce an image or view.