将 UIPanGestureRecognizer 快速限制为边界

Posted 2023-03-13

【中文标题】将 UIPanGestureRecognizer 快速限制为边界

【英文标题】：Limit UIPanGestureRecognizer to boundaries swift

【发布时间】：2019-11-03 16:40:53

【问题描述】：

我在 uicollectionview 单元格中有一个水平滚动的图像，我想实现像 facebook 和照片应用程序苹果这样的功能，你点击图像，它会覆盖整个屏幕。你可以捏和平移图像，我想添加一些限制，就像 facebook 和照片应用程序一样，比如当你捏图片时，你可以最大平移到它的宽度。

如果用户尝试将图像移出边界，我希望图像再次居中。我正在添加一些屏幕截图以提供有关它的想法。

现在我正在使用简单的代码。

 guard gestureRecognizer.view != nil else return
    print(self.imgView.frame)
    if self.imgView.frame.size.width < (self.imgOrignal.width+100) 
        return
    

    let piece = gestureRecognizer.view!
    // Get the changes in the X and Y directions relative to
    // the superview's coordinate space.
    let translation = gestureRecognizer.translation(in: piece.superview)
    if gestureRecognizer.state == .began 
        self.initialCenter = piece.center
    
    // Update the position for the .began, .changed, and .ended states
    if gestureRecognizer.state != .cancelled 
        // Add the X and Y translation to the view's original position.
        let newCenter = CGPoint(x: initialCenter.x + translation.x, y: initialCenter.y + translation.y)
        piece.center = newCenter
    
    else 
        // On cancellation, return the piece to its original location.
        piece.center = initialCenter
    

【参考方案1】：

我已经通过使用 UIScrollView 放大和缩小解决了这个问题，而不是使用捏和平移手势，如果有人想实现该功能，我将在下面添加我的代码。

  func setZoomScale() 
    let widthScale = self.bgView.frame.size.width / self.imgView.bounds.width
    let heightScale = self.bgView.frame.size.height / self.imgView.bounds.height
    let minScale = min(widthScale, heightScale)
    self.imgScrollView.minimumZoomScale = minScale
    self.imgScrollView.zoomScale = minScale



extension YOUR CLASS: UIScrollViewDelegate 

func viewForZooming(in scrollView: UIScrollView) -> UIView? 
    return self.imgView


func scrollViewDidZoom(_ scrollView: UIScrollView) 
    let imageViewSize = self.imgView.frame.size
    let scrollViewSize = scrollView.bounds.size
    let verticalInset = imageViewSize.height < scrollViewSize.height ? (scrollViewSize.height - imageViewSize.height) / 2 : 0
    let horizontalInset = imageViewSize.width < scrollViewSize.width ? (scrollViewSize.width - imageViewSize.width) / 2 : 0
    scrollView.contentInset = UIEdgeInsets(top: verticalInset, left: horizontalInset, bottom: verticalInset, right: horizontalInset)