iOS使用UIGestureRecognizer識別手勢

UIKit中包含了UIGestureRecognizer類，用于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于處理具體的手勢：
1、拍擊UITapGestureRecognizer (任意次數的拍擊)
2、向里或向外捏UIPinchGestureRecognizer (用于縮放)
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對于不同類型的手勢識別器，具有不同的配置屬性。比如UITapGest ureRecognizer，可以配置拍擊次數。界面接收到手勢之后，可以發送一個消息，用于處理響應手勢動作后的任務。當然，不同的手勢識別器，發送的消息方法也會 有所不同。

一個手指，拍擊兩次手勢

// 創建一個手勢識別器
UITapGestureRecognizer *oneFingerTwoTaps =
  [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(oneFingerTwoTaps)] autorelease];

// Set required taps and number of touches
[oneFingerTwoTaps setNumberOfTapsRequired:2];
[oneFingerTwoTaps setNumberOfTouchesRequired:1];
// Add the gesture to the view
[[self view] addGestureRecognizer:oneFingerTwoTaps];
消息方法oneFingerTwoTaps

(void)oneFingerTwoTaps
{
NSLog(@"Action: One finger, two taps");
}</pre> 

 
 兩個手指，拍擊兩次手勢 
 
UITapGestureRecognizer *twoFingersTwoTaps =
[[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingersTwoTaps)] autorelease];
[twoFingersTwoTaps setNumberOfTapsRequired:2];
[twoFingersTwoTaps setNumberOfTouchesRequired:2];
[[self view] addGestureRecognizer:twoFingersTwoTaps];

消息方法twoFingersTwoTaps

(void)twoFingersTwoTaps {
NSLog(@"Action: Two fingers, two taps");
} </pre> 

 
 一個手指向上、向下擦碰手勢 
 
// 向上擦碰
UISwipeGestureRecognizer *oneFingerSwipeUp =
[[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(oneFingerSwipeUp:)] autorelease];
[oneFingerSwipeUp setDirection:UISwipeGestureRecognizerDirectionUp];
[[self view] addGestureRecognizer:oneFingerSwipeUp];


(void)oneFingerSwipeUp:(UISwipeGestureRecognizer *)recognizer
{
CGPoint point = [recognizer locationInView:[self view]];
NSLog(@"Swipe up - start location: %f,%f", point.x, point.y);
}


// 向下擦碰
UISwipeGestureRecognizer *oneFingerSwipeDown =
  [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(oneFingerSwipeDown:)] autorelease];
[oneFingerSwipeDown setDirection:UISwipeGestureRecognizerDirectionDown];
[[self view] addGestureRecognizer:oneFingerSwipeDown];

(void)oneFingerSwipeDown:(UISwipeGestureRecognizer )recognizer
{
CGPoint point = [recognizer locationInView:[self view]];
NSLog(@"Swipe down - start location: %f,%f", point.x, point.y);
}</pre> 

 
 旋轉手勢 
 
UIRotationGestureRecognizer twoFingersRotate =
[[[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingersRotate:)] autorelease];
[[self view] addGestureRecognizer:twoFingersRotate];


(void)twoFingersRotate:(UIRotationGestureRecognizer )recognizer
{
// Convert the radian value to show the degree of rotation
NSLog(@"Rotation in degrees since last change: %f", [recognizer rotation]  (180 / M_PI));
}</pre> 

 
 向里或向外捏的手勢 
 
UIPinchGestureRecognizer *twoFingerPinch =
[[[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingerPinch:)] autorelease];
[[self view] addGestureRecognizer:twoFingerPinch];


(void)twoFingerPinch:(UIPinchGestureRecognizer *)recognizer
{
NSLog(@"Pinch scale: %f", recognizer.scale);
}</pre>