手势处理器UIGestureRecognizer

一 UITapGestureRecognizer

点击手势的处理器有2个属性:

numberOfTapsRequired 点击的次数
numberOfTouchesRequired 点击屏幕手指的个数

for (NSInteger i = 1; i < 6; i++) {
        UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTap:)];
        tapRecognizer.numberOfTapsRequired = i;
        tapRecognizer.numberOfTouchesRequired = 2;
        [self.view addGestureRecognizer:tapRecognizer];
}

上面创建了5个点击手势处理器，如果用2个手指快速点击了屏幕3次，那么会触发3个点击手势处理器的方法(分别是点击屏幕1次，2次，3次对应的手势处理器方法)，这里需要特别注意下

- (void)handleTap:(UITapGestureRecognizer *)recognizer
{
    NSUInteger touchCount = recognizer.numberOfTouches;
    NSUInteger tapCount = recognizer.numberOfTapsRequired;
    NSLog(@"手指个数 %d 触摸次数 %d", touchCount, tapCount);
}

二 UIPinchGestureRecognizer

捏合手势处理器也有2个属性

scale 比例
velocity 速率(scale变大,velocity为正;scale变小,velocity为负)

可以利用捏合手势处理器来实现图片的缩放功能

- (void)handlePin:(UIPinchGestureRecognizer *)recognizer
{
    recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);
    recognizer.scale = 1;
}

三 UIRotationGestureRecognizer

旋转手势处理器有2个属性

rotation 比例(以开始触碰点为基准0，往逆时针方向旋转，rotation变小，往顺时针方向旋转，rotation变大)
velocity 速率(顺时针旋转为正;逆时针旋转为负)

可以利用旋转手势来实现旋转图片的功能

- (void)handleRotation:(UIRotationGestureRecognizer *)recognizer
{
    recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);
    recognizer.rotation = 0;
}

四 UISwipeGestureRecognizer

轻扫手势处理器有2个属性

numberOfTouchesRequired 手指的个数
direction 轻扫的方向(虽然该枚举类型定义为NS_OPTIONS，但是在测试过程中发现在事件处理方法中，如果使用了多个枚举值，则不能有效判断手势的方向，因此如果需要判断多个轻扫手势，则应该是一个方向对应一个手势处理器)

for (NSInteger i = 0; i < 4; i++) {
        UISwipeGestureRecognizer *swipeRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipe:)];
        swipeRecognizer.numberOfTouchesRequired = 1;
        swipeRecognizer.direction = 1 << i;
        [self.view addGestureRecognizer:swipeRecognizer];
}

- (void)handleSwipe:(UISwipeGestureRecognizer *)recognizer
{
    UISwipeGestureRecognizerDirection direction = recognizer.direction;
    if (direction == UISwipeGestureRecognizerDirectionLeft) {
        NSLog(@"向左");
    } else if (direction == UISwipeGestureRecognizerDirectionRight){
        NSLog(@"向右");
    }  else if (direction == UISwipeGestureRecognizerDirectionUp){
        NSLog(@"向上");
    } else if (direction == UISwipeGestureRecognizerDirectionDown){
        NSLog(@"向下");
    }
}

五 UIPanGestureRecognizer

UIPanGestureRecognizer一般用来处理拖动事件，比如拖动一个控件在屏幕上移动

- (void)handlePan:(UIPanGestureRecognizer *)recognizer
{
    CGPoint point = [recognizer translationInView:recognizer.view];
    recognizer.view.transform = CGAffineTransformTranslate(recognizer.view.transform, point.x, point.y);
    [recognizer setTranslation:CGPointZero inView:recognizer.view];
}

六 UILongPressGestureRecognizer

长按手势处理器有两个重要的属性

minimumPressDuration 长按所需的最短时间
allowableMovement 长按手指能移动的最大距离，超出这个

UILongPressGestureRecognizer *longPressRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
longPressRecognizer.minimumPressDuration = 2;
longPressRecognizer.numberOfTouchesRequired = 2;
longPressRecognizer.allowableMovement = 500;
[self.view addGestureRecognizer:longPressRecognizer];

触发长按手势处理器会调用两次对应的方法(开始一次,结束一次),所以需要特别处理下

- (void)handleLongPress:(UILongPressGestureRecognizer *)recognizer
{
    if (recognizer.state == UIGestureRecognizerStateBegan) {
        NSLog(@"UILongPressGestureRecognizer Begin");
    } else if (recognizer.state == UIGestureRecognizerStateEnded) {
        NSLog(@"UILongPressGestureRecognizer End");
    } 
}

七自定义手势处理器

继承 UIGestureRecognizer
引入 #import
在合适的时候设置 self.state = UIGestureRecognizerStateEnded; 来完成自定义手势处理器

下面的例子设计了一个名叫JCGestureRecognizer的手势处理器，当符合从左往右滑动200像素并且滑动过程中上下不超过80像素的浮动的情况，触发该手势处理器。

@interface JCGestureRecognizer : UIGestureRecognizer
@end

#import "JCGestureRecognizer.h"

#import 

@interface JCGestureRecognizer ()
{
    CGPoint startPoint;
}
@end

@implementation JCGestureRecognizer

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [super touchesBegan:touches withEvent:event];
    
    if (touches.count > 1) {
        self.state = UIGestureRecognizerStateFailed;
        return;
    }
    UITouch *touch = [touches anyObject];
    startPoint = [[touches anyObject] locationInView:touch.view];
    
//    self.state = UIGestureRecognizerStateBegan;
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    [super touchesMoved:touches withEvent:event];
    
    if (touches.count > 1) {
        self.state = UIGestureRecognizerStateFailed;
        return;
    }
    
    UITouch *touch = [touches anyObject];
    CGPoint point = [[touches anyObject] locationInView:touch.view];
    
    if (ABS(point.y - startPoint.y) > 80) {
        self.state = UIGestureRecognizerStateFailed;
        return;
    }
    
    if (point.x - startPoint.x > 200) {
        self.state = UIGestureRecognizerStateEnded;
    }
}

@end

使用

JCGestureRecognizer *jcRecognizer = [[JCGestureRecognizer alloc] initWithTarget:self action:@selector(handleJC:)];
[self.view addGestureRecognizer:jcRecognizer];

- (void)handleJC:(JCGestureRecognizer *)recognizer
{
    NSLog(@"JCGestureRecognizer");
}

这里需要特别注意一下，在使用自定义手势的时候，在- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event方法中要非常谨慎的设置self.state = UIGestureRecognizerStateBegan;,如果在刚刚的示例中我们加上这段代码，那么只要有一小点的位移，都会触发handleJC:这个方法，并且会多次调用，此时recognizer的state为UIGestureRecognizerStateBegan，这个信息对我们设计的这个手势处理器来说没有任何用处，因此在这里我们没有设置UIGestureRecognizerStateBegan这个状态，这也给我们一个启发，在手势处理器对应的方法里，首先尽量判断手势的状态，然后根据对应的状态做对应的事情，以免发生不该出现的问题。

八手势的互斥性

比如我们给一个图片添加了一个旋转手势处理器和缩放手势处理器，在没有特殊处理的情况下，如果旋转了图片，那么就不能缩放；如果缩放了图片，就不能旋转了。但我们想要的效果是同时可以旋转和缩放

解决这个方法需要用到UIGestureRecognizerDelegate

设置两个手势处理的委托

pinRecognizer.delegate = self;
rotationRecognizer.delegate = self;

在下面的委托方法中返回YES

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

参考链接

参考1