手势识别

在练手demo中 使用UIImageView原因：之前既能看见图片，又能监听点击的只有UIButton,学了手势，我们的UIImageView也可以。
* tap(代理：左边不能点，右边能点)
* longPress(allowableMovement:触发之前，最大的移动范围)
> 默认调用两次，开始一次，结束一次。
* swipe:(一个手势只能识别一个方向)
* 旋转：
基于上一次旋转
注意:通过transform形变，需要去掉autolayout,才准确
* 复位：(手势的取值都是相对最原始的位置，我们应该是需要相对上一次，因此每次调用，就复位一下，每次都是从零开始旋转角度)
缩放：复位
* 如何同时支持旋转和缩放？默认不支持多个手指，
Simultaneously：同时
当使用一个手势的时候会调用代理的Simultaneously方法，询问是否支持多个手势
* pan
获取平移的位置：translationInView
复位：setTranslation:inView: 需要传一个view，因为点的位置跟坐标系有关系，看他是基于哪个坐标系被清空的。

@interface ViewController ()<UIGestureRecognizerDelegate>代理监听手势

#pragma mark - 手势代理方法
// 是否允许开始触发手势
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
    return NO;
}

// 是否允许同时支持多个手势，默认是不支持多个手势
// 返回yes表示支持多个手势
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

 是否允许接收手指的触摸点
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{
    //获取当前的触摸点
    CGPoint curP = [touch locationInView:self.imageView];
    
    if (curP.x < self.imageView.bounds.size.width * 0.5) {//让imageView的右边能点
        return NO;
    }else{
        return YES;
   }
}

- (void)setUpTap
{
    // 创建点按手势
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tap:)];
    
    tap.delegate = self;
    
    [_imageView addGestureRecognizer:tap];
}

#pragma mark - 长按手势
// 默认会触发两次
- (void)setUpLongPress
{
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];
    
    [self.imageView addGestureRecognizer:longPress];
}

#pragma mark - 清扫
- (void)setUpSwipe
{
    // 默认轻扫的方向是往右
    UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe)];
    swipe.direction = UISwipeGestureRecognizerDirectionUp;
    [self.imageView addGestureRecognizer:swipe];
    // 如果以后想要一个控件支持多个方向的轻扫，必须创建多个轻扫手势，一个轻扫手势只支持一个方向
    // 默认轻扫的方向是往右
    UISwipeGestureRecognizer *swipeDown = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe)];
    swipeDown.direction = UISwipeGestureRecognizerDirectionDown;
    [self.imageView addGestureRecognizer:swipeDown]; 
}

#pragma mark - 旋转手势
- (void)setUpRotation
{
    UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotation:)];
    rotation.delegate = self;
    [self.imageView addGestureRecognizer:rotation];
}

// 默认传递的旋转的角度都是相对于最开始的位置
- (void)rotation:(UIRotationGestureRecognizer *)rotation
{
    
    self.imageView.transform = CGAffineTransformRotate(self.imageView.transform,rotation.rotation);
    
//    (self.imageView.transform, rotation.rotation);
    
    // 复位
    rotation.rotation = 0;
    
    // 获取手势旋转的角度
    NSLog(@"%f",rotation.rotation);
}
#pragma mark - 捏合
- (void)setUpPinch
{
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinch:)];
    pinch.delegate = self;
    [self.imageView addGestureRecognizer:pinch];
}

- (void)pinch:(UIPinchGestureRecognizer *)pinch
{
    self.imageView.transform = CGAffineTransformScale(self.imageView.transform, pinch.scale, pinch.scale);
    
    // 复位
//    
    pinch.scale = 1;
}

#pragma mark - 拖拽
- (void)setUpPan
{
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
    
    
    [self.imageView addGestureRecognizer:pan];
}

- (void)pan:(UIPanGestureRecognizer *)pan
{
    // 获取手势的触摸点
   // CGPoint curP = [pan locationInView:self.imageView];
    
    // 移动视图
    // 获取手势的移动，也是相对于最开始的位置
    CGPoint transP = [pan translationInView:self.imageView];
    
    self.imageView.transform = CGAffineTransformTranslate(self.imageView.transform, transP.x, transP.y);
    
    // 复位
    [pan setTranslation:CGPointZero inView:self.imageView];
    
  //  NSLog(@"%@",NSStringFromCGPoint(curP));
}

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