Apple提供的《iOS human interface guidelines》对于手势（gestures）的定义是：人们使用特定的手指动作来操作基于iOS设备的独特的多触点界面。当你把一个手指放在iPhone/iPad的屏幕上，一个触碰（touch）事件周期便开始了。每次一个手指触碰到屏幕，一个新的touchstart事件开始了。当手指离开屏幕的时候，一个touchend事件开始。当手指接触到屏幕后，如果在屏幕上移动手指，一个touchmove事件触发了。如果过多的手指同时接触屏幕或触碰被其他事件中断，如消息推送，那么touchcancel事件触发了。《iOS human interface guidelines》定义了8种手势，翻译不好，直接把原文搬过来：
Gesture | Action
Tap | To press or select a contro or item(analogous to single mouse click)
Drag | To scroll or pan(that is, move side to side). OR To drag a element.
Flick | To scroll or pan quickly.
Swipe | With one finger, to reveal the Delete button in a table-view row or to reveal Notification Center(from the top edge of the screen).
| With four fingers, to switch between apps on iPad.
Double Tap | To zoom in and center a block of content or an image.
| To zoom out(if already zoomed in).
Pinch | Pinch open to zoom in.
| Pinch close to zoom out.
Touch and hold | In editable or selectable text, to display a magnified view for cursor positioning.
Shake | To initiate an undo or redo action.
Xcode提供了iOS Simulator，位于/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Applications/ 这个simulator可以模拟iPhone/iPad的运行环境。通过将自己的app放到/Users/Library/Application Support/iPhone Simulator/5.1/Applications 文件夹下可以实现该app在模拟器上的运行。
更多关于touch和gesture的解释参见
http://www.sitepen.com/blog/2011/12/07/touching-and-gesturing-on-iphone-android-and-more/
