使用iOS手势UIGestureRecognizer

UIKit中包含了UIGestureRecognizer类，用于检测发生在设备中的手势。UIGestureRecognizer是一个抽象类，定义了所有手势的基本行为，它有下面一些子类用于处理具体的手势：

    1、拍击UITapGestureRecognizer (任意次数的拍击)

    2、向里或向外捏UIPinchGestureRecognizer (用于缩放)

    3、摇动或者拖拽UIPanGestureRecognizer

    4、擦碰UISwipeGestureRecognizer (以任意方向)

    5、旋转UIRotationGestureRecognizer (手指朝相反方向移动)

    6、长按UILongPressGestureRecognizer

对 于不同类型的手势识别器，具有不同的配置属性。比如UITapGestureRecognizer，可以配置拍击次数。界面接收到手势之后，可以发送一个 消息，用于处理响应手势动作后的任务。当然，不同的手势识别器，发送的消息方法也会有所不同。下面列举几个具体示例代码：

1、一个手指，拍击两次手势

// 创建一个手势识别器
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");
}


2、两个手指，拍击两次手势
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");
} 

3、一个手指向上、向下擦碰手势
// 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);
}

4、旋转手势
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));
}

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

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