UIPanGestureRecognizer拖动手势

概述：UIPanGestureRecognizer拖动手势，继承于UIGestureRecognizer类。

手势的配置

/*设置拖动最小手指数，默认为1*/
@property (nonatomic)          NSUInteger minimumNumberOfTouches __TVOS_PROHIBITED;   /*设置拖动最多手指数，默认为UINT_MAX，无限大*/
@property (nonatomic)          NSUInteger maximumNumberOfTouches __TVOS_PROHIBITED; 
  

手势的位置和速度

/*获取拖动的位置*/
- (CGPoint)translationInView:(nullable UIView *)view;
/*设置当前拖动的位置*/
- (void)setTranslation:(CGPoint)translation inView:(nullable UIView *)view;
/*设置拖动的速度，单位：点/秒*/
- (CGPoint)velocityInView:(nullable UIView *)view;   

案例

UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panGestureDetected:)];
[panGestureRecognizer setDelegate:self];
[self.image_view addGestureRecognizer:panGestureRecognizer];

- (void)panGestureDetected:(UIPanGestureRecognizer *)recognizer{
    /*获取状态*/
    UIGestureRecognizerState state = [recognizer state];   
    if (state == UIGestureRecognizerStateBegan || state == UIGestureRecognizerStateChanged)
    {
        /*获取拖动的位置*/
        CGPoint translation = [recognizer translationInView:recognizer.view];
        /*每次都以传入的translation为起始参照*/
        [recognizer.view setTransform:CGAffineTransformTranslate(recognizer.view.transform, translation.x, translation.y)];
       /*设置当前拖动的位置*/
        [recognizer setTranslation:CGPointZero inView:recognizer.view];
        if (self.image_view.frame.size.width <= self.view.bounds.size.width) {
            self.image_view.frame = self.view.bounds;
        }
    }
}

注：了解UIGestureRecognizer类请跳转https://www.jianshu.com/p/e206dc86f89a