UIGestureRecognizer手势

监听触摸事件的做法

如果想监听一个view上面的触摸事件，之前的做法是

自定义一个view

实现view的touches方法，在方法内部实现具体处理代码

通过touches方法监听view触摸事件，有很明显的几个缺点

必须得自定义view

由于是在view内部的touches方法中监听触摸事件，因此默认情况下，无法让其他外界对象监听view的触摸事件

不容易区分用户的具体手势行为

iOS 3.2之后，苹果推出了手势识别功能（Gesture Recognizer），在触摸事件处理方面，大大简化了开发者的开发难度

UIGestureRecognizer

为了完成手势识别，必须借助于手势识别器—-UIGestureRecognizer

利用UIGestureRecognizer，能轻松识别用户在某个view上面做的一些常见手势

UIGestureRecognizer是一个抽象类，定义了所有手势的基本行为，使用它的子类才能处理具体的手势

UITapGestureRecognizer(敲击)

UIPinchGestureRecognizer(捏合，用于缩放)

UIPanGestureRecognizer(拖拽)

UISwipeGestureRecognizer(轻扫)

UIRotationGestureRecognizer(旋转)

UILongPressGestureRecognizer(长按)

UITapGestureRecognizer点击

每一个手势识别器的用法都差不多，比如UITapGestureRecognizer的使用步骤如下

创建手势识别器对象

UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] init];

设置手势识别器对象的具体属性

// 连续敲击2次

tap.numberOfTapsRequired = 2;

// 需要2根手指一起敲击

tap.numberOfTouchesRequired = 2;

添加手势识别器到对应的view上

[self.iconView addGestureRecognizer:tap];

监听手势的触发

[tap addTarget:self action:@selector(tapIconView:)];

设置UIImageView可以点击，且只能左边可以点击

// 点按
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tap)];

tap.delegate = self;

[_imageView addGestureRecognizer:tap];

// 是否允许接收手指
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
// 获取手指的触摸点
CGPoint curP = [touch locationInView:self.imageView];

// 左边能点
if (curP.x < self.imageView.bounds.size.width * 0.5) {
return YES;
}else{

return NO;
}

}

UILongPressGestureRecognizer长按

- (void)setUpLongPress
{
// 长按
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];

[self.imageView addGestureRecognizer:longPress];
}

// 长按图片的时候就会触发长按手势 会调用多次
- (void)longPress:(UILongPressGestureRecognizer *)longPress
{
// 一般开发中,长按操作只会做一次
// 假设在一开始长按的时候就做一次操作

if (longPress.state == UIGestureRecognizerStateBegan) {

NSLog(@"%ld",longPress.state);
}

}

UISwipeGestureRecognizer轻扫

注意：一个手势对象对应一个手势，一个控件可以同时添加多个手势

// 轻扫
- (void)setUpSwipe
{
// 轻扫
// 一个手势只能支持一个方向
UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
// 轻扫方向:默认是右边
swipe.direction = UISwipeGestureRecognizerDirectionUp;

[self.imageView addGestureRecognizer:swipe];

UISwipeGestureRecognizer *swipeD = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
// 轻扫方向:下边
swipeD.direction = UISwipeGestureRecognizerDirectionDown;

[self.imageView addGestureRecognizer:swipeD];

}

- (void)swipe:(UISwipeGestureRecognizer *)swipe
{
if (swipe.direction == UISwipeGestureRecognizerDirectionDown) {
NSLog(@"下");
}else{

}
NSLog(@"%s",__func__);
}

UIPanGestureRecognizer拖拽

注意：复位

// 拖拽
- (void)setUpPan
{
// 拖拽
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];

[self.imageView addGestureRecognizer:pan];

}

- (void)pan:(UIPanGestureRecognizer *)pan
{
// 返回的是相对于最原始的手指的偏移量

CGPoint transP = [pan translationInView:self.imageView];

NSLog(@"%@",NSStringFromCGPoint(transP));
// 移动图片控件
self.imageView.transform = CGAffineTransformTranslate(self.imageView.transform, transP.x, transP.y);

// 复位,表示相对上一次
[pan setTranslation:CGPointZero inView:self.imageView];
}

UIRotationGestureRecognizer旋转

注意复位

// 旋转
- (void)setUpRotation
{
// 旋转
UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotation:)];

rotation.delegate = self;

[self.imageView addGestureRecognizer:rotation];
}

- (void)rotation:(UIRotationGestureRecognizer *)rotation
{
NSLog(@"%f",rotation.rotation);

self.imageView.transform = CGAffineTransformRotate(self.imageView.transform, rotation.rotation);
// 复位
rotation.rotation = 0;
}

UIPinchGestureRecognizer捏合（放大缩小）

注意复位

- (void)setUpPinch
{
// 捏合
UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinch:)];
pinch.delegate = self;

[self.imageView addGestureRecognizer:pinch];
}

- (void)pinch:(UIPinchGestureRecognizer *)pinch
{
NSLog(@"%f",pinch.scale);
self.imageView.transform = CGAffineTransformScale(self.imageView.transform, pinch.scale, pinch.scale);

// 复位
pinch.scale = 1;

}

默认状态下，一个控件只能支持一种手势，当需要同时支持多个手势时，比如：同时旋转，放大缩小，需要设置手势的代理方法

// Simultaneously:同时
// 是否允许同时支持多个手势
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
return YES;
}