UIKit中包含了UIGestureRecognizer類，用於檢測發生在設備中的手勢。UIGestureRecognizer是一個抽象類，定義了所有手勢的基本行為，它有下面一些子類用於處理具體的手勢：

    1、拍擊UITapGestureRecognizer (任意次數的拍擊) 
    2、向裡或向外捏UIPinchGestureRecognizer (用於縮放) 
    3、搖動或者拖拽UIPanGestureRecognizer 
    4、擦碰UISwipeGestureRecognizer (以任意方向) 
    5、旋轉UIRotationGestureRecognizer (手指朝相反方向移動) 
    6、長按UILongPressGestureRecognizer

對於不同類型的手勢識別器，具有不同的配置屬性。比如UITapGestureRecognizer，可以配置拍擊次數。界面接收到手勢之後，可以發送一個消息，用於處理響應手勢動作後的任務。當然，不同的手勢識別器，發送的消息方法也會有所不同。
[代碼] 一個手指，拍擊兩次手勢
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// 創建一個手勢識別器
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UITapGestureRecognizer *oneFingerTwoTaps =
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  [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(oneFingerTwoTaps)] autorelease];
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// Set required taps and number of touches
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[oneFingerTwoTaps setNumberOfTapsRequired:2];
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[oneFingerTwoTaps setNumberOfTouchesRequired:1];
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// Add the gesture to the view
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[[self view] addGestureRecognizer:oneFingerTwoTaps];
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消息方法oneFingerTwoTaps
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- (void)oneFingerTwoTaps
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{
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  NSLog(@"Action: One finger, two taps");
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}
[代碼] 兩個手指，拍擊兩次手勢
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UITapGestureRecognizer *twoFingersTwoTaps =
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  [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingersTwoTaps)] autorelease];
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[twoFingersTwoTaps setNumberOfTapsRequired:2];
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[twoFingersTwoTaps setNumberOfTouchesRequired:2];
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[[self view] addGestureRecognizer:twoFingersTwoTaps];
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消息方法twoFingersTwoTaps
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- (void)twoFingersTwoTaps {
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  NSLog(@"Action: Two fingers, two taps");
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}
[代碼] 一個手指向上、向下擦碰手勢
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// 向上擦碰
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UISwipeGestureRecognizer *oneFingerSwipeUp =
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  [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(oneFingerSwipeUp:)] autorelease];
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[oneFingerSwipeUp setDirection:UISwipeGestureRecognizerDirectionUp];
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[[self view] addGestureRecognizer:oneFingerSwipeUp];
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- (void)oneFingerSwipeUp:(UISwipeGestureRecognizer *)recognizer
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{
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  CGPoint point = [recognizer locationInView:[self view]];
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  NSLog(@"Swipe up - start location: %f,%f", point.x, point.y);
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}
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// 向下擦碰
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UISwipeGestureRecognizer *oneFingerSwipeDown =
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  [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(oneFingerSwipeDown:)] autorelease];
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[oneFingerSwipeDown setDirection:UISwipeGestureRecognizerDirectionDown];
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[[self view] addGestureRecognizer:oneFingerSwipeDown];
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- (void)oneFingerSwipeDown:(UISwipeGestureRecognizer *)recognizer
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{
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  CGPoint point = [recognizer locationInView:[self view]];
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  NSLog(@"Swipe down - start location: %f,%f", point.x, point.y);
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}
[代碼] 旋轉手勢
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UIRotationGestureRecognizer *twoFingersRotate =
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  [[[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingersRotate:)] autorelease];
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[[self view] addGestureRecognizer:twoFingersRotate];
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- (void)twoFingersRotate:(UIRotationGestureRecognizer *)recognizer
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{
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  // Convert the radian value to show the degree of rotation
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  NSLog(@"Rotation in degrees since last change: %f", [recognizer rotation] * (180 / M_PI));
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}
[代碼] 向裡或向外捏的手勢
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UIPinchGestureRecognizer *twoFingerPinch =
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  [[[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingerPinch:)] autorelease];
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[[self view] addGestureRecognizer:twoFingerPinch];
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- (void)twoFingerPinch:(UIPinchGestureRecognizer *)recognizer
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{
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  NSLog(@"Pinch scale: %f", recognizer.scale);
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}