IOS中我们可以通过UITouch进行触摸事件监听，但是UITouch实现捏合、旋转、长按等手势事件监听非常麻烦。IOS中提供
UIGestureRecognizer的子类帮我们简洁等实现捏合、旋转等特殊手势监听。并且一个视图可添加多个不同等手势监听器。
开启userInteractionEnabled
IOS 中UIView 默认是不可响应事件的，我们需要开启
userInteractionEnabled方可进行事件响应。下面代码中我们创建了一个图片视图，并且开始事件响应。UIView 通过addGestureRecognizer进行添加手势监听器和removeGestureRecognizer删除手势监听器
// 创建图片视图
- (void) creareImg {UIImage* image = [UIImage imageNamed:@"zz.jpeg"];_imageView = [[UIImageView alloc] initWithImage:image];UIScreen* screen = [UIScreen mainScreen];const int width = 200;const int height = 100;const float x = screen.bounds.size.width / 2 - width / 2;const float y = screen.bounds.size.height / 2 - height;_imageView.frame = CGRectMake(x, y, width, height);_imageView.userInteractionEnabled = YES;[self.view addSubview:_imageView];
}
了解UIGestrueRecognizer
在开始使用自定义手势之前我们先了解一下
UIGestrueRecognizer的，因为自定义都是基于UIGestrueRecognizer继承实现的。UIGestrueRecognizer是一个手势监听器，它可以设置多个手指同时触发触发事件等行为。它具有代理协议UIGestureRecognizerDelegate下面我来看一下它主要的属性和API、代理方法。
属性
| 名称 | 类型 | 说明 | 默认值 |
|---|---|---|---|
| state | UIGestureRecognizerState | 当前手势状态，可分为手势开始，手势改变，手势结束等等 | |
| enabled | BOOL | 是否启用 | YES |
| view | UIView | 手势监听的视图 | |
| requiresExclusiveTouchType | BOOL | 是否忽略其他手势类型，设置为YES将只响应一种手势类型 | NO |
| numberOfTouches | NSUInteger | 多少根手指触发手势 | 1 |
API
- (instancetype)initWithTarget:(nullable id)target action:(nullable SEL)action初始化并添加事件监听函数- (void)addTarget:(id)target action:(SEL)action添加事件监听函数- (void)removeTarget:(nullable id)target action:(nullable SEL)action删除事件监听函数- (void)requireGestureRecognizerToFail:(UIGestureRecognizer *)otherGestureRecognizer添加其他手势冲突失效器，当触发当前手势时，指定的手势将失效。- (CGPoint)locationInView:(nullable UIView*)view获取相对于指定视图的坐标位置- (CGPoint)locationOfTouch:(NSUInteger)touchIndex inView:(nullable UIView*)view获取指定手指相对指定视图的坐标位置
代理协议
-
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer手势准备开启时候触发，返回NO则取消手势。 -
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer当手势与其他手势同时发生识别时候触发，返回YES运行两个手势同时进行，返回NO则阻止同时识别。 -
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch是否给事件接收手指。在手势开始触发事件触发前触发，返回NO可以阻止事件获取触摸的手指。 -
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceivePress:(UIPress *)press是否给按下事件接收手指，在按下手势事件触发前触发。返回NO可阻止事件获取触摸的手指。
我们了解清除GestureRecognizer 类，下面我们来了解其子类手势的使用。
UITapGestureRecognizer 点击手势
点击手势，可设置手指数量、点击次数触发的手势
// 创建点击手势
- (void) createTapGes {_imageView.userInteractionEnabled = YES; // 开启响应事件属性UITapGestureRecognizer* tapOneGes = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(big)]; // 创建手势tapOneGes.numberOfTapsRequired = 1; // 触发事件的点击次数tapOneGes.numberOfTouchesRequired = 1; // 触发事件的手指数量[_imageView addGestureRecognizer:tapOneGes]; // 添加手势监听器
}
// 点击触发事件
- (void) big {UIScreen* screen = [UIScreen mainScreen];[UIView beginAnimations:nil context:nil]; // 开始布局动画_imageView.frame = CGRectMake(0, 0, screen.bounds.size.width, screen.bounds.size.height);[UIView commitAnimations]; // 结束布局动画
}
UIPinchGestureRecognizer 捏合手势
捏合手势，表示双指捏合缩放的手势触发。常用于对图片查看缩放事件监听
// 捏合手势
- (void) createPinchGes {UIPinchGestureRecognizer* pinch = [[UIPinchGestureRecognizer alloc] init]; // 创建手势[pinch addTarget:self action:@selector(scale:)]; // 添加事件函数pinch.delegate = self; // 设置代理[_imageView addGestureRecognizer:pinch]; // 视图添加手势监听器
}- (void) scale: (UIPinchGestureRecognizer*) pinch {UIView* IView = pinch.view; // 获取监听的视图CGAffineTransform transiform = CGAffineTransformScale(IView.transform, pinch.scale, pinch.scale); // 计算缩放后的矩阵if (transiform.a < 0.4) { // 缩放小于0.4阻止transiform.a = 0.4;transiform.d = 0.4;}IView.transform = transiform; // 重新设置矩阵pinch.scale = 1; // 重置缩放矩阵，否则手势会一直累加
}// 添加允许多个手势触发代理函数
- (BOOL) gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {return YES;
}
上面代码中我们通过获取捏合手势的scale 属性获取用户捏合缩放的大小。并且使用内置api CGAffineTransformScale 重新计算了视图的2D矩阵（矩阵表示图像变形，可以了解一下图形学），注意！最后一步中必须重置手势的scale 否则会一直累加导致计算矩阵错误，如果不想重置的话那就需要修改 CGAffineTransformScale的第一个参数为基础矩阵参数。
UIRotationGestureRecognizer 旋转手势
旋转手势，可获取用户手指旋转的角度。
// 旋转手势
- (void) createRotateGes {UIRotationGestureRecognizer* rotate = [[UIRotationGestureRecognizer alloc] init];[rotate addTarget:self action:@selector(rotate:)];rotate.delegate = self;[_imageView addGestureRecognizer:rotate];
}
// 旋转触发事件
- (void) rotate: (UIRotationGestureRecognizer*) rotate {UIView* IView = rotate.view;IView.transform = CGAffineTransformRotate(IView.transform, rotate.rotation); // 重新计算视图矩阵rotate.rotation = 0;
}
UIPanGestureRecognizer 平移手势
平移动手势，比较简单就是手指移动时候触发，但是提供平移的位置和平移的速度
// 平移手势
- (void) createPanGes {UIPanGestureRecognizer* pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];pan.delegate = self;[_imageView addGestureRecognizer:pan];
}
- (void) pan: (UIPanGestureRecognizer*)pan {CGPoint speed = [pan velocityInView:_imageView]; // 获取移动速度NSLog(@"x速度= %f, y速度= %f", speed.x, speed.y);CGPoint translation = [pan translationInView:_imageView]; // 获取移动矩阵CGAffineTransform transform = CGAffineTransformTranslate(_imageView.transform, translation.x, translation.y);_imageView.transform = transform;
}
UILongPressGestureRecognizer 长按手势
长按对应视图触发手势，可设置手指数量和手指长按时间
// 长按手势
- (void) createLongPassGes {UILongPressGestureRecognizer* longPass = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(pass:)];longPass.minimumPressDuration = 1; // 设置长按触发时间，默认0.5[_imageView addGestureRecognizer: longPass];
}- (void)pass: (UILongPressGestureRecognizer*) longPass {if (longPass.state == UIGestureRecognizerStateBegan) {NSLog(@"开始长按");} else if (longPass.state == UIGestureRecognizerStateEnded) {NSLog(@"结束长按");} else if (longPass.state == UIGestureRecognizerStateChanged) {NSLog(@"长按发生改变");}
}
UISwipeGestureRecognizer 轻滑手势
轻滑手势，类似我们的平移手势。但是轻滑不同的是在用户快速滑动时候速度，并且只提供滑动方向。
// 创建轻滑手势
- (void) createSwipe {UISwipeGestureRecognizer* swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swiper:)];swipe.direction = UISwipeGestureRecognizerDirectionDown;[_imageView addGestureRecognizer: swipe];swipe.delegate = self;
}- (void) swiper: (UISwipeGestureRecognizer*)swiper {NSLog(@"发生向下滑动");
}
