关于ios:IOS-定义手势监听器详解利用-UIGestureRecognizer-进行捏合旋转平移点击长按手势事件响应

IOS 中咱们能够通过 UITouch 进行触摸事件监听，然而 UITouch 实现捏合、旋转、长按等手势事件监听十分麻烦。IOS 中提供 UIGestureRecognizer 的子类帮咱们简洁等实现捏合、旋转等非凡手势监听。并且一个视图可增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，咱们须要开启 userInteractionEnabled 方可进行事件响应。上面代码中咱们创立了一个图片视图，并且开始事件响应。UIView 通过 addGestureRecognizer 进行增加手势监听器和 removeGestureRecognizer 删除手势监听器

// 创立图片视图
- (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];
}

理解 UIGestrueRecognizer

在开始应用自定义手势之前咱们先理解一下 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，它能够设置多个手指同时触发触发事件等行为。它具备代理协定 UIGestureRecognizerDelegate 上面我来看一下它次要的属性和 API、代理办法。

属性

API

• - (instancetype)initWithTarget:(nullable id)target action:(nullable SEL)action 初始化并增加事件监听函数
• - (void)addTarget:(id)target action:(SEL)action 增加事件监听函数
• - (void)removeTarget:(nullable id)target action:(nullable SEL)action 删除事件监听函数
• - (void)requireGestureRecognizerToFail:(UIGestureRecognizer *)otherGestureRecognizer 增加其余手势抵触生效器，当触发以后手势时，指定的手势将生效。
• - (CGPoint)locationInView:(nullable UIView*)view 获取绝对于指定视图的坐标地位
• - (CGPoint)locationOfTouch:(NSUInteger)touchIndex inView:(nullable UIView*)view 获取指定手指绝对指定视图的坐标地位

代理协定

• - (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer 手势筹备开启时候触发，返回 NO 则勾销手势。
• - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer 当手势与其余手势同时产生辨认时候触发，返回 YES 运行两个手势同时进行，返回 NO 则阻止同时辨认。
• - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch 是否给事件接管手指。在手势开始触发事件触发前触发，返回 NO 能够阻止事件获取触摸的手指。
• - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceivePress:(UIPress *)press 是否给按下事件接管手指，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。

咱们理解革除 GestureRecognizer 类，上面咱们来理解其子类手势的应用。

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

// 创立点击手势
- (void) createTapGes {
    _imageView.userInteractionEnabled = YES; // 开启响应事件属性
    UITapGestureRecognizer* tapOneGes = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(big)]; // 创立手势
    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]; // 增加手势监听器
}
// 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]; // 完结布局动画
}

UIPinchGestureRecognizer 捏合手势

捏合手势，示意双指捏合缩放的手势触发。罕用于对图片查看缩放事件监听

// 捏合手势
- (void) createPinchGes {UIPinchGestureRecognizer* pinch = [[UIPinchGestureRecognizer alloc] init]; // 创立手势
    [pinch addTarget:self action:@selector(scale:)]; // 增加事件函数
    pinch.delegate = self; // 设置代理
    [_imageView addGestureRecognizer:pinch]; // 视图增加手势监听器
}

- (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; // 从新设置矩阵
    pinch.scale = 1; // 重置缩放矩阵，否则手势会始终累加
}

// 增加容许多个手势触发代理函数
- (BOOL) gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {return  YES;}

下面代码中咱们通过获取捏合手势的 scale 属性获取用户捏合缩放的大小。并且应用内置 api CGAffineTransformScale 从新计算了视图的 2D 矩阵（矩阵示意图像变形，能够理解一下图形学），留神！最初一步中必须重置手势的scale 否则会始终累加导致计算矩阵谬误，如果不想重置的话那就须要批改 CGAffineTransformScale 的第一个参数为根底矩阵参数。

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); // 从新计算视图矩阵
    rotate.rotation = 0;
}

UIPanGestureRecognizer 平移手势

平挪动手势，比较简单就是手指挪动时候触发，然而提供平移的地位和平移的速度

// 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]; // 获取挪动速度
    NSLog(@"x 速度 = %f, y 速度 = %f", speed.x, speed.y);
    CGPoint translation = [pan translationInView:_imageView]; // 获取挪动矩阵
    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工夫

// 长按手势
- (void) createLongPassGes {UILongPressGestureRecognizer* longPass = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(pass:)];
    longPass.minimumPressDuration = 1; // 设置长按触发工夫，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(@"完结长按");
    } else if (longPass.state == UIGestureRecognizerStateChanged) {NSLog(@"长按产生扭转");
    }
}

UISwipeGestureRecognizer 轻滑手势

轻滑手势，相似咱们的平移手势。然而轻滑不同的是在用户疾速滑动时候速度，并且只提供滑动方向。

// 创立轻滑手势
- (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(@"产生向下滑动");
}