IOS开发之手势-UIGestureRecognizer

在 iPhone 或 iPad 的开发中，除了用 touchesBegan / touchesMoved / touchesEnded 这组方法来控制使用者的手指触控外，也可以用 UIGestureRecognizer 的衍生类別来进行判断。用 UIGestureRecognizer 的好处在于有现成的手势，开发者不用自己计算手指移动轨迹。UIGestureRecognizer的衍生类別有以下几种：

• UISwipeGestureRecognizer       手指在屏幕上很快的滑动
• UITapGestureRecognizer          轻触
• UIPanGestureRecognizer          手指的拖动
• UIPinchGestureRecognizer        两个指头捏或者放的操作
• UIRotationGestureRecognizer    手指反向操作
• UILongPressGestureRecognizer 在一点上长按

从命名上不难了解這些类別所对应代表的手势，分別是 Tap（点一下）、Pinch（二指往內或往外拨动）、Rotation（旋转）、Swipe（滑动，快速移动）、Pan （拖移，慢速移动）以及 LongPress（长按）。這些手势別在使用上也很简单，只要在使用前定义并添加到对应的视图上即可。

UISwipeGestureRecognizer

UISwipeGestureRecognizer* recognizer; 
// handleSwipeFrom 是偵測到手势，所要呼叫的方法  
recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom)]; 
// 不同的 Recognizer 有不同的实体变数 
// 例如 SwipeGesture 可以指定方向 
//右：UISwipeGestureRecognizerDirectionRight
//上：UISwipeGestureRecognizerDirectionUp
//下：UISwipeGestureRecognizerDirectionDown
//左：UISwipeGestureRecognizerDirectionLeft 
recognizer.direction = UISwipeGestureRecognizerDirectionUp;
[self.view addGestureRecognizer:recognizer];


//--------------------------手势方法----------------------------------------------------------------------
- (void)handleSwipeFrom:(UISwipeGestureRecognizer*)recognizer 
{    
// 触发手勢事件后，在这里作些事情     
// 底下是刪除手势的方法    
[self.view removeGestureRecognizer:recognizer]; 
}
//--------------------------------------------------------------------------------------------------------

UITapGestureRecognizer 

UITapGestureRecognizer *recognizer=[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapFrom:)]; 
[infoView addGestureRecognizer:recognizer];


//--------------------------手势方法----------------------------------------------------------------------
-(void)handleTapFrom:(UITapGestureRecognizer *)recognizer
{ 
    NSLog(@">>>tap it"); 
}
//--------------------------------------------------------------------------------------------------------

UIPanGestureRecognizer 

UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(handlePan:)];
[snakeImageView addGestureRecognizer:panGestureRecognizer];  


//--------------------------手势方法----------------------------------------------------------------------
-(void)handlePan:(UITapGestureRecognizer *)recognizer
{ 
    CGPoint translation = [recognizer translationInView:self.view];  
    recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,recognizer.view.center.y + translation.y);  
    [recognizer setTranslation:CGPointZero inView:self.view]; 
//拖动(pan手势)速度(以较快的速度拖放后view有滑行的效果)
        if (recognizer.state == UIGestureRecognizerStateEnded) {  
          
        CGPoint velocity = [recognizer velocityInView:self.view];  
        CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));  
        CGFloat slideMult = magnitude / 200;  
        NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult);  
          
        float slideFactor = 0.1 * slideMult; // Increase for more of a slide   
        CGPoint finalPoint = CGPointMake(recognizer.view.center.x + (velocity.x * slideFactor),  
                                         recognizer.view.center.y + (velocity.y * slideFactor));  
        finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width);  
        finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height);  
          
        [UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{  
            recognizer.view.center = finalPoint;  
        } completion:nil]; 
/*
拖动(pan手势)速度代码实现解析：

1. 计算速度向量的长度（估计大部分都忘了）这些知识了。
2. 如果速度向量小于200，那就会得到一个小于的小数，那么滑行会很短
3. 基于速度和速度因素计算一个终点
4. 确保终点不会跑出父View的边界
5. 使用UIView动画使view滑动到终点

*/

}
//--------------------------------------------------------------------------------------------------------

UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(handlePinch:)];
[snakeImageView addGestureRecognizer:*pinchGestureRecognizer ];  


//--------------------------手势方法----------------------------------------------------------------------
-(void)handlePinch:(UITapGestureRecognizer *)recognizer
{ 
    recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);  
    recognizer.scale = 1; 
}
//--------------------------------------------------------------------------------------------------------

UIRotationGestureRecognizer 

UIRotationGestureRecognizer *rotateRecognizer = [[UIRotationGestureRecognizer alloc]initWithTarget:self action:@selector(handleRotate:)];  
[snakeImageView addGestureRecognizer:rotateRecognizer];  
 
//--------------------------手势方法----------------------------------------------------------------------
-(void)handleRotate:(UITapGestureRecognizer *)recognizer
{ 
    recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);  
    recognizer.rotation = 0;
}
//--------------------------------------------------------------------------------------------------------

UILongPressGestureRecognizer 

UILongPressGestureRecognizer *longPressGR =[[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
//长按３秒后触发事件
longPressGR.minimumPressDuration = 3;
[self.view addGestureRecognizer:longPressGR];


//--------------------------手势方法----------------------------------------------------------------------
-(void)handleLongPress:(UITapGestureRecognizer *)recognizer
{ 
    NSLog(@">>>LongPress it"); 
}
//--------------------------------------------------------------------------------------------------------

手势的依赖性

//如果双击确定偵測失败才會触发单击    
[singleRecognizer requireGestureRecognizerToFail:doubleRecognizer];